An Italian restaurant offers a small, medium, and a large pizza. The choices for toppings are cheese, sausage, spinach or vegetables. How many different pizzas can you order?
Assuming that one or more toppings are allowed
We can have 2 ways for the cheese, that is, take it or leave it
we can have 2 ways for the sausage
we can have 2 ways for spinach
we can have 2 ways for veggies
so the number of ways for the toppings = 2*2*2*2 = 16
Now, that will include the cases of NO toppings, do we want that?
Each of those 16 ways can be in either small, medium or large
number of possible pizzas = 3*16 = 48
see the note about no toppings at all, how many would there be in that case?