Question

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

Answer 1

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