2x = 8(y + 1) ---> 2x = (23)(y + 1) ---> 2x = 2(3y + 3) ---> x = 3y + 3
9y = 3(x - 9) ---> (32)y = 3(x - 9) ---> 32y = 3(x - 9) ---> 2y = x - 9 ---> x = 2y + 9
Combining these two equations: 3y + 3 = 2y + 9 ---> y = 6
If y = 6 then x = 3y + 3 ---> x = 21