-5x+7y=5x+2y
x=-5
y=?
what is y

y = -10

Step-by-step explanation:

Step 1:  Substitute -5 for x in the equation -5x + 7y = 5x + 2y

-5x + 7y = 5x + 2y

-5(-5) + 7y = 5(-5) + 2y

Step 2:  Solve for y

-5(-5) + 7y = 5(-5) + 2y

25 + 7y + 25 - 7y = -25 + 2y + 25 - 7y

50 / -5 = -5y / -5

-10 = y

 y = -10

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