What is the anwere to this problem in the simple form

It is in simple form. There is absolutely nothing more that can be done, unless it is a joke. And math jokes are very hard to come by.

I don't think that y(y - 1)/(a + 2b) is any simpler.

Come to think of it, is that x^2 or y^2 on the top left. 
I think my first answer is the best one. Nothing can be done.