simplify the given expressions, then make a list of the like terms that appear in your final answer

3(r^2+2p-p^3)-(6r^2+p^3-p)
and
4^n+4n-4n^2 + (2^n-2n)

Take it a bit at a time.

Write 3(r^2+2p-p^3) so that there are no brackets.

Now write -(6r^2+p^3-p) so there are no brackets.

Now add both together, bringing together the r^2, p and p^3 terms.