Hi guys! I'm back with another probability problem I've struggling on. Please DO NOT leave any links or you will be reported. Please help explain what I'm doing wrong and what I'm suppose to do. This is confusing me.

Pizza parlor A advertises 35 different​ three-topping pizzas. How many individual toppings does Pizzeria A actually​ use? Pizzeria B advertises 55 different​ two-topping pizzas. How many toppings does pizza parlor B actually​ use? ​(Hint​: In these​ problems, you are given the total number of​ combinations, and you must find the number of toppings that are​ used.)

Pizza parlor A uses nothing different toppings. ​(Type a whole​ number.)

Thank to anyone who decides to help :) ​