I am trying to study for the accuplacer, but I am not understanding the steps to get the answers to some problems.

1. solve for n: a

^{2}+n+2b^{2}=(a+b)(a+2b)2. (x

^{3}y^{5}-xy^{4}+x^{2}y^{2}) / (xy)3. (x

^{5}y^{7}-xy^{4}) / (xy)4. x

^{3}+6x+8x5. t(t-2)-3t(t-2)

Any help is appreciated! If there are any links that might help me to understand these questions is welcomed too.