Solve the simultaneous equations
4x + y = 20
x - y = 15

X=7

y= -8

Step-by-step explanation:

4x+y+(x-y)=20+15

4x+y+x-y=35

plus y and minus y cancels out.

4x+X= 35

5x=35

X= 7

Substitute X=7 in any equation

x-y=15

7-y=15

y=-8

for b its (t) and c its (d)

step-by-step explanation:

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