Question

I am having trouble solving this problem via Elimination Method.
y = -7+0
y = 1x-21

Answer 1

(y=-7)*-1
y=-21+1x
-y=7
y=-21+1x
0=-14+1x......>14=x
substituted to 2nd equation y=1(14)-21=-7
check -7=-7+0 .....>-7=-7