First thing you want to do is distrubute those negatives signs...doing that, you'll get

Now, you should group like terms...m squared, n squareds go together, m squared ns should go together...so on

Now, combine like terms

gets

Now, about this. Is this supposed to be

2) 2x (A+B)y - (A+B)y^2 / 8(A+B)

or

?? Can't tell by the way you wrote it...