Question

X-y=1
X+y=3 Elimination

Answer 1

x-y=1
x+y=3
You see the y's can cancel out. So add it together and you have:
2x=4
x=2
Now that you have x, plug it in to one of the equations to find y.
I will plug it into the first one.
(2)-y=1
-y=-1
y=1