The number of single topping pizza that can be made from 2 styles of crust, 3 types of sauce, and 9 choices of toppings can be obtained as follows:
2 styles can be selected in 2 ways
3 sauces can be selected in 3 ways
9 toppings can be selected in 9 ways
2 x 3 x 9 = 72 ways
