HELP PLS ASAP I WILL GIVE 50 points and brainliest PLS The variable z varies jointly with x and y. Also, z = -75 when x = 3 and y = -5.

What equation describes this variation?
z = kxy
What is the constant of variation?
k =

Step-by-step explanation:

z = kxy, where k is a real constant.

We have z = -75, x = 3, y = -5.

(-75) = k(3)(-5)

-75 = -15k

k = 5.

use an equation of ratios to determine the amount of gas needed to fill the tank.

    0.2             0.8

  =    

288.75             x

                                                              231 gal

so, 0.2x = (0.8)(288.75 gal), and x = = 1155 gal.

                                                                0.2

it would take 1155 gal. to fill the tank.

the cost would be

1155 gal         $3

* = $3465   (answer)

      1           1 gal

hope this you