answer
x = -2
y = 2
simply the equations and rewrite both in terms of y
−8x + 4y = 24 divide both sides by 4
-2x + y = 6
y = 2x + 6
−7x+7y=28 divide both sides by 7
-x + y = 4
y = x + 4
set both equations equal to each other
y = 2x + 6
y = x + 4
y = 2x + 6 = x + 4
solve
2x + 6 = x + 4 subtract x from both sides
x + 6 = 4
x = -2
plug x back into one of the equations
x = -2
y = x + 4
y = -2 + 4
y = 2
x = -2, y = 2
