perform indicated operation then express in lowest terms?

Question

r^2-9 over 3t times 9t^2 over r-3

Answer 1

You have to factor r^2 - 9 into (r+3)(r-3).
Then it will cancel the (r-3) on the bottom of the other fraction, and one t from t^2 cancels the t on the bottom of the first, and the 9 cancels the 3 on the bottom of the first to a 3 and a 1

So you get (r+3)3t over 1 which is just 3t(r+3)

Answer 2

Possibly
((r^2 - 9)/3t)(9t^2)/(r - 3) =
(r + 3)(r - 3)(9t^2)/(3t) =
(r + 3)3t

Answer 3

you get (r +3) over 27t^3