solve for x and y

Question

x+y=-1

x+2y=0

Answer 1

System:

(1): x+y = -1

(2): x+2y = 0

Solution:

(3)=(2)-(1): (x+2y) - (x+y) = 0 - (-1)

                    x + 2y - x - y = 1

                    y = 1

Now substitute into (1).

x + 1 = -1

x = -2

So the solution is x = -2, y = 1.