The answers are:
P(9, 2) = 72
P(5, 5) = 120
P(7, 7) = 5040
These are examples of permutations. The problems are asking us to find the total number of ways an event can happen.
In the first case, P(9, 2), we are asked to find the ways that 2 things can be chosen out of a group of 9.
9 x 8 = 72
P(5, 5) = 5 x 4 x 3 x 2 x 1
P(7, 7) = 7 x 6 x 5 x 4 x 3 x 2 x 1
