Use elimination and subtitution method to solve the problem. First, eliminate x and you'll find the value of y x - 4y = 12 x - y = 0 --------------- - (substract) -3y = 12 y = 12/-3 y = -4
Second, subtitute -4 as y and you'll find the value of x x - y = 0 x- (-4) = 0 x + 4 = 0 x = -4