2x + y = 5 and x + y = 4
If you need to find x and y, then you can rearrange the equations like so:
x = 4 - y
lets plug this into the first equation:
2(4 - y) + y = 5
8 - 2y + y = 5
8 - 1y = 5
-1y = -3
y = 3
So now that we have y, we can plug it into either equation to get x:
x + 3 = 4
x = 1