The amount of money it takes to fill up a gas tank varies directly with the number of gallons bought. it cost $21.87 to fill up a car with gasoline with 9 gallons of gasoline. what is the constant of variation?

$2.43 per gallon of gas.

Step-by-step explanation:

We have been given that the amount of money it takes to fill up a gas tank varies directly with the number of gallons bought.

We know that the equation for two directly proportional quantities is in form: , where,

k = The constant of variation and y is directly proportional to x.

To find the constant of variation for our given equation, we will substitute the given values in above equation as:

Let us divide both sides of our equation by 9 gallons.

Therefore, the constant of variation is $2.43 per gallon of gas.

circle area = pi * radius^2

if diameter = 10 then radius = 5

circle area = pi * 5^2

circle area = pi * 25

circle area = 78.5398163397 square units

step-by-step explanation:

option c) graph of line going through 1, 4 and 3, 10

step-by-step explanation:

let y equal to margo's coin collection

let x equal to number of years

at the begining x=0, y=1 → point=(x,y)→point=(0,1)

she adds 3 coins per year, then y=1+3x

at x=1, y=1+3(1)=1+3→y=4→point=(x,y)→point=(1,4)

at x=3, y=1+3(3)=1+9→y=10→point=(x,y)→point=(3,10)

the graph of line going through (1, 4) and (3, 10), then the option c is the correct.