1. If you are trying to find x, then you simply set each equation equal to each other, because they are both equal to y.
x + 6 = -2x - 3
x = -2x - 9
3x = -9
x = -3
2. Now you have to rearrange each equation to be qual to y
equation 1:
5x - y = -5
5x = -5 + y
5x + 5 = y
equation 2:
3x - 6y = 24
3x = 24 + 6y
3x - 24 = 6y
x/2 - 4 = y
then set them equal
x/2 - 4 = 5x + 5
x/2 = 5x + 9
x/2 = 10x/2 + 9
-9x/2 = 9
-9x = 18
x = -2