-2x - 2y = 0 --------------------------(1)
-x + 4y = 40 --------------------------(2)
Multiply through equation (2) by 2
-2x + 8y = 80 --------------------------(3)
subtract equation (1) from (2)
10y = 80
Divide both-side of the equation by 10
y = 8
subtsitute y = 8 into equation (2) and then solve for x
-x + 4(8) = 40
-x + 32 = 40
subtract 32 from both-side of the equation
-x = 40 - 32
-x =8
Multiply both-side by -1
x = -8