2y = 2x + 12
y = -2x - 3
You have the value of y in the second equation
So you can substitute it in the first equation and find the value of x
2(-2x - 3) = 2x + 12
2(-2x) - 2(3) = 2x + 12
-4x - 6 = 2x = 12
You can add 6 to both sides and subtract 2x from both sides to find x
-4x - 6 + 6 = 2x + 12 + 6
-4x = 2x + 18
-4x - 2x = 2x - 2x + 18
-6x = 18
Divide both sides by -6
x = -3
Substitute x in equation (2) to find y
y = -2(-3) -3
y = 3
The solution is (-3, 3)