Using the combination formula, the number of ways to order the pizzas in each case is given as follows:
a) 638 ways if Grogg must order at least five toppings.
b) 937,024 ways if each pizza must have at least three toppings.
c) 1024 ways if Lizzie's pizza must have at least four toppings and Grogg's must have at least one topping. Iraqi Dinar Guru