Find x and y for simultaneous equations: x+y=1 and 2x+3y=5

Multiply x+y=1 by 2, to give 2x+2y=2. Subtract 2x+2y=2 from 2x+3y=5, giving y=3.Substitute y=3 into x+y=1, giving x=-2.This gives the solution x=-2 and y=3.