Lemme help ya boi,
2x + 3y = -11
2y + 12 = x
If x = 2y + 12 than we can put it into the first equation:
2(2y + 12) + 3y = -11
4y + 24 + 3y = -11
7y + 24 = -11
7y = -35
y = -5
We now plug -5 for y:
2x + 3(-5) = -11
2x - 15 = -11
2x = 4
x = 2
Enjoy comrade...