Answer: 5
Explanation:
Given : The total number of toppings for the plain cheese base.= 3
The different types of pizzas can be made by using the 3 toppings is given by using combinations:-
Using 1 topping at a time =

Using 2 topping at a time =

Using all 3 topping at a time =

Also,

Then, The number of different types of pizzas can be made by using the 3 toppings will be :-

Hence, the umber of different types of pizzas can be made by using the 3 toppings =5