Answer:
455
Step-by-step explanation:
This is a combination problem: we need to create groups of 3 elements from the pool of 15 options, and the order of the elements in the group doesn't matter.
So, to solve the problem, we need to find the combination of 15 choose 3:
C(15,3) = 15! / (3! * 12!) = (15*14*13)/(3*2) = 455
We can make 455 different 3-topping sundaes.