2x + y = 5 5x + 3y = 11 solve by addition?
Write that as two equations.
2x + y = 11
55x + 3y = 11
Multiply the first equation by 3 and then subtract.
6x + 3y = 33
49x = -22
That leads to the value of x. Then use any equation for y.
When you wrote 5 5x did you mean to write 5x or 55x? If you meant 5x + 3y = 11, then you end up with
x = 22 y = -33