Solve for both systems - 2x - 4y = 20 and 4x - 4y = 20

4x - 4y = 20

4x - 4y+4y = 20+4y

4x= 20+4y

4x/4= 20+4y/4

x=5+y

- 2x - 4y = 20

- 2(5+y) - 4y = 20

- 2(5) (-2)(+y) - 4y = 20

-10-2y- 4y = 20

-10- 6y = 20

-10- 6y+10 = 20+10

-6y=30

-6y/-6=30/-6

y=-5

x=5+y

x=5+(-5)=0