Why can you use cross products to solve the proportion StartFraction 18 over 5 EndFraction = StartFraction x over 100 EndFraction for x?

Answers

Answer 1
45
djekdkdkfkfkktkffk
Answer 2

Answer:

45

Step-by-step explanation:


Related Questions

SCALCET8 3.9.003. Each side of a square is increasing at a rate of 4 cm/s. At what rate is the area of the square increasing when the area of the square is 9 cm2

Answers

Answer: [tex]24\ cm^2/s[/tex]

Step-by-step explanation:

Given

Each side of square is increasing at a rate of 4 cm/s

Side of a square when area is [tex]9\ cm^2[/tex]

Suppose a is side of the square

[tex]\Rightarrow a=\sqrt{9}\\\Rightarrow a=3\ cm[/tex]

Area is given by

[tex]\Rightarrow A=a^2\\\text{Differentiate area w.r.t time}\\\\\Rightarrow \dfrac{dA}{dt}=2a\dfrac{da}{dt}\\\\\Rightarrow \dfrac{dA}{dt}=2\times 3\times 4\\\\\Rightarrow \dfrac{dA}{dt}=24\ cm^2/s[/tex]

Area is increasing at a rate of [tex]24\ cm^2/s[/tex]

Answer:

24cm^2/ s

Step-by-step explanation:

The strength of one's immune system can be evaluated in several ways. One of the most popular methods involves measuring the concentration of adenosine triphosphate (ATP) in the blood. In women, the mean blood ATP level is 390 ng/mL, and the standard deviation is 115 ng/mL. It has been hypothesized that women with Major Depressive Disorder (MDD) have decreased immune function. A recent study found that a random sample of 30 women with MDD had an average blood ATP level of 355 ng/mL. Using a one-sample z test, what is the p-value of this result? (HINT: This involves a one-tailed hypothesis test).

Answers

Answer:

Hence the value of p is 0.04746.

Step-by-step explanation:

The test statistic is

[tex]Z=(\bar x-\mu)/(s/vn)\\\\=(355-390)/(115/ \sqrt(30))\\\\=-1.667[/tex]

The p-value= P(Z<-1.67) =0.04746. (from standard distribution table)

Therefore p-value =0.04746.

You are watching an airplane fly in the distance.The airplane is traveling at altitude of 8 kilometers How far is the airplane from your location?

Answers

8km
Distance from your location = the airplane’s altitude.

What type of line is PQ⎯⎯⎯⎯⎯⎯⎯⎯?

Answers

Answer:

median

Step-by-step explanation:

Q is at the midpoint of RS and so PQ is a median

A median is a segment from a vertex to the midpoint of the opposite side.

We want to define what type of line is PQ (the line that passes through points P and Q) by looking at the given image, one can easily see that the line PQ is a median, now let's explain why.

First, let's analyze the image:

In the image, we can see that P is one vertex of the triangle, and Q is the midpoint of the segment RS (you can see that RQ = 4 and QS = 4) , where R and S are the other two vertexes of the triangle.

Particularly, we can define a median of a triangle as the line that passes through the midpoint of one side of the triangle and by the vertex that does not belong to that side.

With that definition, we can see that PQ is a median because Q is the midpoint of one side of the triangle and P is the vertex that does not belong to that side.

If you want to learn more, you can read:

https://brainly.com/question/2272632

What is the solution to the linear equation?
-12 + 3b - 1 = -5 - b

Answers

Answer:

b=2

Step-by-step explanation:

b = 2

Rearrange:
3b - 13 = -b - 5

Eliminate b from right side:
3b - 13 + b = -b - 5 + b

4b - 13 = -5

Eliminate 13 on the left:
4b - 13 + 13 = -5 + 13

4b = 8

Simplify:
8 / 4 = 2

b = 2

Rohit thinks of a 4 digit number. The digit in the one’s place is 3 more than the digit in the ten’s place, but 5 less than the digit in the thousand’s place. The value of the hundred’s place is 600. The digit in thousand’s place is the greatest odd number. What is the number Rohit is thinking of?

Answers

Answer:

9614

Step-by-step explanation:

Generic number with 4 digit

1000t + 100h + 10y + x

x = 3 + y

x = m - 5

h = 6

m = 9

if we substitute the value we have:

x = 9 - 5 = 4

4 = 3 + y

y = 1

Final number

9614

suppose △abc≅△xyz. what is the corresponding congruent part for each segment or angle?​

Answers

Answer:

See below

Step-by-step explanation:

Hi there!

We're given that ΔABC≅ΔXYZ

When two triangles are congruent, their corresponding parts are congruent

Because of that, it means vertex A in ΔABC is congruent to vertex X in ΔXYZ, vertex B is congruent to vertex Y, and vertex C is congruent to vertex Z

Since we don't have a picture of the triangles given, we can use the names of the triangles to find the corresponding parts

so, to find the corresponding congruent angle to <BCA:

B is the first letter in the angle, and the corresponding letter in ΔXYZ is Y.

C is the second letter in the angle, and the corresponding letter is Z.

A is the last letter in the angle, and the corresponding letter is X

so that means <YZX is congruent to <BCA

now let's do the same for <ZYX

Z is the first letter in the angle, and the corresponding letter that's in the same place in ΔABC is C

Y is the second letter in the angle, and the corresponding letter is B

X is the last letter in the angle, and the corresponding letter is A

So that means <CBA is congruent to <ZYX

Now to find corresponding sides:

We can still use the names of the triangles, ΔABC and ΔXYZ

so to find the corresponding side to AB,

in ΔABC, AB makes up the first and second letter of the name of the triangle

The corresponding side must also make up the first and second letter of the name of the triangle

in ΔXYZ, the letters X and Y make up the first and second letter

so that means XY must be corresponding to AB

finally,

we need to find the segment congruent to YZ

in ΔXYZ, YZ makes up the second and third letter of the name of the triangle

the corresponding side must also make up the second and third letter of the name of the triangle

in ΔABC,  the letters B and C make up the second and third letter in the triangle

So that means BC must be congruent to YZ

Hope this helps!

chang knows one side of a triangle is 13 cm which set of two sides is possible for the length of the other two sides

5 cm and 8 cm
6cm and 7 cm
7cm and 2 cm
8cm and 9 cm​

Answers

Answer:

i dont knowwww dhehje ejhdjeke jsienje

Answer:

8cm and 9 cm​

Step-by-step explanation:

Sum of sides rule:

The sum of the two smallest sides of a triangle has to be greater than the third side.

5 cm and 8 cm

One side is 5, other 8, 5 + 8 = 13. The sum has to be greater than 13, so this is not possible.

6cm and 7 cm

6 + 7 = 13, same as above, not possible.

7cm and 2 cm

7 + 2 = 9 < 13, so not possible.

8cm and 9 cm​

8 + 9 = 17 > 13, so possible, and this is the answer.

Johnny tripled his baseball card collection. Then he added 6 more cards to the collection. Now he has 24 cards. How many cards did he start with?

Answers

9514 1404 393

Answer:

  6

Step-by-step explanation:

Work backward.

If he has 24 after adding 6, he had 18 before that addition.

If he had 18 after tripling his collection, he had 18/3 = 6 cards to start with.

__

Note that this is the same process you would use if you started with an equation.

  3c +6 = 24 . . . . where c is the number of cards Johnny started with

  3c = 24 -6 = 18 . . . . . subtract 6 from the final number

  c = 18/3 = 6 . . . . . . . . divide the tripled value by 3 to see the original value

Johnny started with 6 cards.

All I need is number one

Answers

Answer:

a. 7 ÷ 4 yes

b. 4 ÷ 7 no

c. [tex]\frac{7}{4}[/tex] yes

d. [tex]\frac{4}{7}[/tex] no

e. 7 × [tex]\frac{1}{4}[/tex] yes

f. [tex]1\frac{3}{4}[/tex] yes

Step-by-step explanation:

hope this helps ^^

The figure below is a rhombus.
w = [? ]°

Answers

Answer:

Step-by-step explanation:

7 is added to the product of 5 and 6​

Answers

Answer:

37

Step-by-step explanation:

7 + (5×6)

= 7 + 30

= 37

.................

Answer:

37

Step-by-step explanation:

First Step: Multiply

5x6=30

Second Step: Add

30+7=37

Therefore your answer is 37

Hope this helps and if it does, don't be afraid to give my answer a "Thanks" and maybe a Brainliest if it's correct?  

What is the factored form of x2 − 4x − 5?

(x + 5)(x − 1)
(x + 5)(x + 1)
(x − 5)(x − 1)
(x − 5)(x + 1)

Answers

Answer:

x2 - 4x - 5 factored form is (x - 5)(x + 1)

Answer:

(x − 5)(x + 1)

Step-by-step explanation:

The answer above is correct.

What is the y-intercept of the line given by y=4x - 6

Answers

The y-intercept for this line is (0, -6)

Answer:

y= -6

Step-by-step explanation:

the y-intercept is -6, which corresponds to point (0,-6)

remember that you're using the

y=mx+b format of an equation of a line where b is the y-intercept.

Also, if you make x=0, y will be -6.

If 89 babies are sampled at random from the hospital, what is the probability that the mean weight of the sample babies would differ from the population mean by less than 48 grams

Answers

Answer:

0.6836

Step-by-step explanation:

(weight - mean weight) = 48

Variance, s² = 204,304

Sample size, n = 89

We need to obtain the Zscore :

Zscore = (X - mean) / standard Error

Zscore = (weight - mean weight ) / (s/√n)

s = √204304 = 452

The difference from the meanncoukdnbe either to the right or left :

Zscore = - 48 / (452/√89) OR 48 / (452/√89)

Zscore = - 48 / 47.911904 OR - 48 / 47.911904

Zscore = - 1.002 or 1.002

P(Z < - 1.002) = 0.1582 (using Z table)

P(Z < 1.002) = 0.8418

P(Z < 1.002) - P(Z < - 1.002)

0.8418 - 0.1582

= 0.6836

The Sureset Concrete Company produces concrete. Two ingredients in concrete are sand (costs $6 per ton) and gravel (costs $8 per ton). Sand and gravel together must make up exactly 75% of the weight of the concrete. Also, no more than 40% of the concrete can be sand and at least 30% of the concrete be gravel. Each day 2000 tons of concrete are produced. To minimize costs, how many tons of gravel and sand should be purchased each day

Answers

Answer:

The Sureset Concrete Company

The tons of gravel and sand that should be purchased each day are:

Sand = 800 tons

Gravel = 700 tons

Step-by-step explanation:

Two ingredients for producing concrete = sand and gravel

Cost of sand per ton = $6

Cost of gravel per ton = $8

Sand and gravel = 75% of the concrete

Therefore 25% (100 - 75%) will be made up of cement and water

Tons of concrete produced each day = 2,000

Sand and gravel = 1,500 (2,000 * 75%)

Sand <= 40% of 2,000 = 800 tons

Gravel => 30% of 2,000 = 700 (1,500 - 800) tons

To minimize costs,  800 tons of gravel and 700 tons of sand should be purchased each day.

Total cost incurred daily for both sand and gravel = $10,400 (800 * $6 + 700 * $8)

Ayuda porfavor !!!!!!!!

Answers

Answer:

La hipotenusa del triángulo mide 5 metros, el ángulo (a) mide 53,13º y el ángulo (b) mide 36,87º.

Step-by-step explanation:

Dado que del triángulo rectángulo se conocen sus dos catetos, uno mide 4 metros y el otro 3 metros, para hallar su hipotenusa y sus ángulos interiores se deben realizar los siguientes cálculos:

4^2 + 3^2 = X^2

16 + 9 = X^2

√25 = X

5 = X

sen(a) = 4/5

(a) = 53,13º

(b) = 180 - (90º+53,13º)

(b) = 36,87º

Así, la hipotenusa del triángulo mide 5 metros, el ángulo (a) mide 53,13º y el ángulo (b) mide 36,87º.

If one card is drawn from a deck, find the probability of getting these results.
Enter your answers as fractions or as decimals rounded to 3 decimal places.

Answers

Answer:

Face card= 12/52

(52 cards in a deck and 12 are face cards)

Red face card= 6/12

(12 face cards in a deck cards in a deck and 6 are red face cards)

Black face card= 6/52

(6 are black)

Black card= 26/52

(52 cards in a deck and 26 are black)

Red card= 26/52

(26 are red)

Which of the following choices is the average speed of a tourist who traveled for 1 hour on a plane at 400 mph and 4 hours by car at 60 mph?

(average= total miles/total hours)

Answers

Answer:

128 mph

Step-by-step explanation:

1 hour = 400

4 hours = 240

240+400= 640

4+1 = 5

640/5=128

One jar holds 20 green marbles and 4 white marbles. A second jar holds 60 black marbles and 20 white marbles. What is the probability that a white marble will be drawn from both jars?

Answers

Answer:

[tex]\sf \dfrac{1}{24}=0.0417=4.17\%\:\:(3\:s.f.)[/tex]

Step-by-step explanation:

Given information:

Contents of Jar 1:

20 green marbles4 white marblestotal marbles = 20 + 4 = 24

Contents of Jar 2:

60 black marbles20 white marblestotal marbles = 60 + 20 = 80

Probability Formula

[tex]\sf Probability\:of\:an\:event\:occurring = \dfrac{Number\:of\:ways\:it\:can\:occur}{Total\:number\:of\:possible\:outcomes}[/tex]

Therefore:

[tex]\sf P(white\:marble\:from\:Jar\:1)=\dfrac{4}{24}=\dfrac{1}{6}[/tex]

[tex]\sf P(white\:marble\:from\:Jar\:2)=\dfrac{20}{80}=\dfrac{1}{4}[/tex]

As the events are independent (i.e. drawing a marble from one jar does not influence or affect drawing a marble from the other jar), we can use the independent probability formula:

[tex]\sf P(A\:and\:B)=P(A) \cdot P(B)[/tex]

Therefore, the probability that a white marble will be drawn from both jars is:

[tex]\sf P(white\:marble\:from\:Jar\:1)\:and\:\sf P(white\:marble\:from\:Jar\:2)=\dfrac{1}{6} \cdot \dfrac{1}{4}=\dfrac{1}{24}[/tex]

#Jar 1

Total marbles =20+4=24

P(w)

4/24=1/6

#Jar 2

Total marbles=60+20=80

P(w)

20/801/4

P(w in total)

1/4(1/6)1/24

The half-life of a newly discovered radioactive element is 30 seconds. To the nearest tenth of a second, how long will it take for a sample of 9 grams to decay to 0.72 grams

Answers

Answer:

It will take about 109.3 seconds for nine grams of the element to decay to 0.72 grams.

Step-by-step explanation:

We can write a half-life function to model our function.

A half-life function has the form:

[tex]\displaystyle A=A_0\left(\frac{1}{2}\right)^{t/d}[/tex]

Where A₀ is the initial amount, t is the time that has passes (in this case seconds), d is the half-life, and A is the amount after t seconds.

Since the half-life of the element is 30 seconds, d = 30. Our initial sample has nine grams, so A₀ is 9. Substitute:

[tex]\displaystyle A=9\left(\frac{1}{2}\right)^{t/30}[/tex]

We want to find the time it will take for the element to decay to 0.72 grams. So, we can let A = 0.72 and solve for t:

[tex]\displaystyle 0.72=9\left(\frac{1}{2}\right)^{t/30}[/tex]

Divide both sides by 9:

[tex]\displaystyle 0.08=\left(\frac{1}{2}\right)^{t/30}[/tex]

We can take the natural log of both sides:

[tex]\displaystyle \ln(0.08)=\ln\left(\left(\frac{1}{2}\right)^{t/30}\right)[/tex]

By logarithm properties:

[tex]\displaystyle \ln(0.08)=\frac{t}{30}\ln(0.5)[/tex]

Solve for t:

[tex]\displaystyle t=\frac{30\ln(0.08)}{\ln(0.5)}\approx109.3\text{ seconds}[/tex]

So, it will take about 109.3 seconds for nine grams of the element to decay to 0.72 grams.

Find the equivalent expression using the
same bases.
(98.41)

Answers

9684.5281 I think that’s the answer

In the diagram, point D is the center of the medium-sized circle that passes through C and E, and it is also the center of the largest circle that passes through A and G. Each of the diameters of the small circles with centers B and F equals the radius of the medium-sized circle with center D. The shaded area is what fraction of the largest circle?Single choice. ​

Answers

9514 1404 393

Answer:

  5/8

Step-by-step explanation:

The area of the smaller circles is proportional to the square of the ratio of their diameters. The two smallest circles have diameters equal to 1/4 the diameter of the largest circle. Hence their areas are (1/4)^2 = 1/16 of that of the largest circle.

Similarly, the medium circle has a diameter half that of the largest circle, so its area is (1/2)^2 = 1/4 of the are of the largest circle.

The smaller circles subtract 2×1/16 +1/4 = 3/8 of the area of the largest circle. Then the shading is 1-3/8 = 5/8 of the area of the largest circle.

which of the following is the median of 19, 31, 15, 50, 20​

Answers

the answer would be 20

[tex]\huge\textsf{Hey there!}[/tex]

[tex]\large\text{19, 31, 15, 50, \& 20}[/tex]

[tex]\large\text{When you see or hear the word \underline{median}, think of the question}\\\large\text{asking you \bf what is the MIDDLE NUMBER.}\large\text{To find the}\\\large\text{middle number you have to put the numbers from descending}\\\large\text{(least/decreasing) or ascending (greatest/increasing) order}[/tex]

[tex]\large\text{15, 19, 20, 31, \& 20}[/tex]

[tex]\large\text{Make sure it is even on BOTH SIDES of the DATA SET}[/tex]

[tex]\large\text{It seems to be even on both sides of the number \bf 20}\large\text{ so \underline{20}}\\\large\text{can be your median/middle number in this given set}[/tex]

[tex]\boxed{\boxed{\huge\textsf{Answer: the median is \bf 20}}}\huge\checkmark[/tex]

[tex]\large\text{Good luck on your assignment and enjoy your day!}\\\\\\\\\\\frak{Amphitrite1040:)}[/tex]

If f(1) =160 and f(n+1)=-2f(n),
What is f(4)?

Answers

Answer:

f(n+1=-2f(n)

f(x)=-2f(n)

f(4)

f(4)=-2f(4)

Answer:

f(4) = - 1280

Step-by-step explanation:

Using the recursive rule and f(1) = 60 , then

f(2) = - 2f(1) = - 2 × 160 = - 320

f(3) = - 2f(2) = - 2 × - 320 = 640

f(4) = - 2f(3) = - 2 × 640 = - 1280

insert a digit in a place of each "..." to make numbers that are divisible by 6 if it is possible: 4...6

Answers

Answer:

1 There is no number that make it divisible by 6 with no decimals

2 1,4,7

Step-by-step explanation:

2 23718/6= 3953

 23748/6= 3958

 23778/6= 3963

What is the y-intercept of the graph of y = 2.5x? a. 2.5 c. 0 b. 1 d. -1

Answers

Answer:

answer is C

Step-by-step explanation:

General equation of a line is expressed as shown:

y = mx+c where;

m is the slope or gradient of the line

c is the intercept of the line

Given the equation of the line graph as y =2.5x

Comparing the given equation with the general equation, it is seen that m = 2.5 and c = 0 (since there is no value for the intercept)

Based on the explanation, the y-intercept of the graph is therefore 0

Answer:

B

Step-by-step explanation:

To find the x-intercept, substitute in

0 for y and solve for x

To find the y-intercept, substitute in 0 for x and solve for y

x-intercept(s): None

y-intercept(s): (0,1)

The last dividend paid by Wilden Corporation was $1.55. The dividend growth rate is expected to be constant at 1.5% for 2 years, after which dividends are expected to grow at a rate of 6.0% forever. The firm's required return (rs) is 12.0%. What is the best estimate of the current stock price?

Answers

Answer:

Net present value= $25.17

Step-by-step explanation:

We are told that The last dividend paid was $1.55 and that the dividend growth rate is constant at 1.5% for 2 years.

Thus;

1) After 1st year;

1.55 × (1 + 0.015) = 1.57325 Div1

After 2nd year;

1.57325 × (1 + 0.015) = 1.59685 Div2

After that 2 years it grows at 6% Constant rate forever;

1.59685 × (1 + 0.06) = 1.69266 Div3

Let's now use the dividend formula which grows in perpetuity at a rate of "g" since required return is 12%:

Thus;

V = 1.69266/(0.12 - 0.06) = 28.211

Thus; Div2 = 28.211 + 1.59685 ≈ 29.80785

Now, using the financial calculator of the Cash Flow function, we have:

Div0 = 0

Div1 = 1.57325

Div2 = 29.80785

i% = 12

Net present value = (1.57325/(1 + 0.12)) + ((1.59685 + 28.211)/(1 + 0.12)²)

Net present value= $25.17

Solve, then check algebraically and graphically. 9x-3=78

Answers

Answer:

[tex]9x - 3 = 78 \\ 9x - 3 + 3 = 78 + 3 \\ 9x = 81 \\ \frac{9x}{9} = \frac{81}{9} \\ x = 9[/tex]

Answer:

[tex]9x - 3 = 78 \\9 x = 78 + 3 \\ 9x = 81 \\ x = \frac{81}{9} \\ x = 9[/tex]

Write an expression for the sequence of operations described below.
divide s by u, add the result to t, then add v to what you have
Do not simplify any part of the expression

Answers

Step-by-step explanation:

s+u

Add t: You will need to introduce brackets

(s+u) + t

Add v: Introduce another v

((s/u) + t) + v

Other Questions
Adam smith suggested that increase competition will allow prices to be keptA. Umeasurable B. HighC. LowD. None of these Cartier was to the French and _________ as Cabot was to the English and ______. A. Ft. Caroline/Maine.B. St. Lawrence/Labrador.C. St. Augustine/Virginia.D. Cape Fear/Florida. 2. ' ' ? ) What do you mean by Random Sampling? What are the two methods of drawing a Random Sample? Explain any one in detail. \\ What anchored cach round beneath the water level? Find the inverse of the function y = x2 12 Name a textile factory in Massachusetts, which ran on water power, and employed young low-skilled women. a. Lowell Factory. b. Lancaster Textiles. c. Vanderbilt Textiles. d. American Factory. What is this part of the graphic novel about?DISSE'S REPORT WAS BY FAR THE BEST. IT WAS A LETTER TOATHER IN WHICH SHE PROMISED TO TAKE CARE OF HER MOTHERITTLE BROTHERWhat central idea does this page convey to readers?What elements does the author use to develop thecentral idea?From Persepolis by Marjane Satrapi A confided aquifer has a piezometric height of 30 feet before being pumped. The well is then pumped at 250 gallons/day for a very long time and results in a drawdown of 10 feet at the well. If the transmissivity in the aquifer is 10.0 ft2/day and the radius of the well is 0.5 feet, estimate the drawdown in feet for a well 50 feet away Disabled people should depend ----- others suitable preposition The ________ function is responsible for making sure customers are aware of the company's products. Group of answer choices Find the value of y in the equation y=-4x+9 when x=-3 If 260 people donated $10.00 to an organization how much money would said organization have received in total? What are the intercepts of the graphed function?3-2O x-intercept = (-1,0)y-intercept = (-3,0)O x-intercept = (0, -1)y-intercept = (0, -3)O x-intercept = (0, -1)y-intercept = (-3,0)x-intercept = (-1,0)y-intercept = (0, -3)6 Translate to English: EL CUMPLEAOS DE ENRIQUECuando entran en el restaurante, Conchita, llevando su mejor vestido,sientan a la mesa. Enrique tiene mucha hambre y la paella es deliciosa.muy guapa y todo el mundo mira al joven matrimonio. Los dos seConchita est muy alegre y habladora.Esta tarde tengo mucha sed. Me gustaria un poco de vino,-Tendrs una botella del mejor vino.Alas once menos diez llegan al teatro donde representan la obra de unator clsico del siglo diecisiete.una de la maana, hora en que Enrique y Conchita vuelven al piso, muyAlas once se levanta el teln y empieza la funcin que dura hasta lacontentos de haber pasado una tarde tan agradable.Y Enrique contesta: Under the Articles of Confederation, Congress was unable to pass laws without a two-thirds vote from the states. Identify the level of measurement of the data, and explain what is wrong with the given calculation. Ina set of data, alert levels are represented as 1 for low, 2 for medium, and 3 for high. The average mean of the 522 alert levels is 1.3. The data are at the ________ level of measurement. a. Nominalb. Ordinalc. Ratiod. IntervalWhat is wrong with the given calculation?a. Such data should not be used for calculations such as an average.b. One must use a different method to take the average of such datac. The true average is 2.5d. There is nothing wrong with the given calculation. What characteristics of christianity enabled it to grow and ultimately to triumph as the official religion of the Roman empire Simplify:-4a + 2(a + 9)A. -2a + 9B. -2a + 18C. 2a + 9D. 2a + 18 5.34x10 to the 27th power molecules of sulfur hexafluoride to moles of sulfur hexafluoride