The first equation x=y-8 is, subtract y from each side, x-y=-8the second equation -x-y=0 is, multiply by -1, x+y=0Now add and get 2x+0=-8 or 2x=-8 or x=-4 Use this result in the second equation to get -4+y=0 or y=4Or subtract the equations to get 0-2y=-8 or y=4