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