-3x + 3y = 24
x + 2y = 13
(x + 2y) - 2y = 13 - 2y
x = 13 - 2y
-3(13 - 2y) + 3y = 24
-39 + 6y + 3y = 24
9y - 39 = 24
(9y - 39) + 39 = 24 + 39
9y = 63
9y ÷ 9 = 63 ÷ 9
y = 7
x + 2y = 13
x + 2(7) = 13
x + 14 = 13
(x + 14) - 14 = 13 - 14
x = -1
When x = -1
y = 7
An easy way to check:
-3x + 3y = 24
-3(-1) + 3(7) = 24
3 + 21 = 24
24 = 24
Since it is the same on both sides, our answers are correct.
