Answer:
Easiest way to do this is to get the X's on one side of the equals sign and the Y's on the other. Then, you can choose the one with the negative sign in it.
When you do that,
First one is 2x=0+y, or y = 2x
Second one is 2y=0+x, or 2y = x (weird right)
Third one is x=0+2y, or 2y = x (again, weird right)
Final one is 2y=0-x, or 2y = -x
The final one is the answer. Cheers, but don't forget to remember this for next time bro.