Solve each system by elemination, 4x+8y=20 and - 4x+2y=-30

The sum of the left side of these two equations is equal to the same of the right side is these two equations

4x+8y + (-4x+2y) = 20 + 30

10y = 50 (x is eliminated)

y=5

Take this into the second equation

-4x + 2y = 30

-4x + 2*5 = 30

x=-5

So x=-5

y=5