Problem : Calculate the following:
a) P(12, 7)
b) P(3, 2)
c) P(7, 4)
d) P(8, 8)

a) 3991680
b) 6
c) 840
d) 40320

Problem : Calculate the following:
a) C(12, 7)
b) C(3, 2)
c) C(7, 4)
d) C(8, 8)

a) 792
b) 3
c) 35
d) 1

Problem : Andrew owns 11 shirts. In how many different ways can he dress in 7 days?

P(11, 7) = 1663200 different ways.

Problem : Alexandra can bake 6 different types of cookies. She has to bring 4 different kinds to a bake sale. How many combinations can she bring?

C(6, 4) = 15 different ways.

Problem : C(13, 5) = C(13, x). If x≠5, what is x?

x = 8.