Question 40766
1st) 2x+y=0 
2nd) x-2y=-10

Multiply the 1st by 2 to get:
4x+2y=0
Add that to the 2nd to get:
 5x=-10
 x=-2
Substitute that into 1st or 2nd to solve for Y, as follows:
2(-2)+y=0
y=4
Check the answer in the 2nd: -2-2(4)=-10
It checks.
Cheers,
Stan H.