Solve for both systems: 3x+3y=21 and 8x + y = 21

3x+3y=21

3x+3y-3y=21 -3y

3x=21 -3y

3x/3=21 -3y/3

x=7-y

8x + y = 21

8(7-y) + y = 21

8(7) (8)(-y) + y = 21

56 -8y+ y = 21

56 -7y= 21

56 -7y-56= 21-56

-7y=-35

-7y/-7=-35/-7

y=5

x=7-y

x=7-5=2