Answer:
there are 120 different sundaes with three toppings you can order.
Explanation:
If the chosen toppings must be different, then that means it's a Combination where the order doesn't matter (as long as they're all different).
Equation: 10C3
Forming Equation: 10!/(10-3)!*3!=10*9*8*7!/7!*3!=10*9*8/6=720/6=120
Therefore, there are 120 different sundaes with three toppings you can order.