At this site, you cannot EASILY show fractions in this form \(\displaystyle \dfrac{m + n}{p + q}\). If that is what you mean, type [m + n] / [p + q].
I very much doubt that what you show above is what anything looks like in your book.
MMM told you to use brackets to define expressions and / to indicate division. You can see what is in your book, but we cannot. You must make it clear.
Is this the problem?
\(\displaystyle Simplify\ \dfrac{a^{2p} * a^{p-1} - a^p}{a^{3p} - a^p}\)
If it is, show it as [a^(2p) * a^(p-1) - a^p] / [a^(3p) - a^p]. Otherwise, we are guessing about what the problem is.
Assuming THAT is the problem, the first step I would do is to factor
\(\displaystyle \dfrac{a^{2p} * a^{p-1} - a^p}{a^{3p} - a^p} = \dfrac{a^p(a^p * a^{(p-1)} - 1)}{a^p(a^{2p} - 1)}.\)
But this may be ALL wrong because you have not made clear what the problem is.