Answer:
x = 6, y = -6
Step-by-step explanation:
solve for x and y
x + 3y = -12
y + 3 = -x + 3
add
(x + 3y) + -x + 3 = -12 + y + 3
3y + 3 = y - 9
2y + 3 = -9
2y = -12
y = - 6
x + 3(-6) = -12
x - 18 = -12
x = 6
