What you can do here is use the Elimination method.
You can add the two equations together, and since -4x and 4x cancel out, you're left with 9y = -36
y would then equal -4
Then you can substitute in -4 for y in any of the equations.
-4x + 2(-4) = -12
-4x - 8 = -12
-4x = -4
x = 1