What if you had ten toppings available. How many different two-topping pizza variations can you make ...
What definition did you have to "adjust" in order to get David's answer of 55?
Do you agree that this is a fair interpretation of the problem?
10 pizza toppings Choose any 2 - different or same; How many choices?
Ans: 55 Why?
— David Marain (@dmarain)