x = 134, y= 81
You have
x + y = 215
x - y = 53
You can use elimination or substitution for these equations;
If you add the two equations above y is eliminated and you can solve for x
In the second equation
x - y = 53
x = 53 + y
If you substitute 53 + y in to the first equation you can solve it for y.
I hope this helps if you have any questions send me a message.