How to solve this problem. i don’t know how to do this and need desperately

There are 4 possibilities for cone or cup to hold your ice cream.  There are 3 different sizes to choose from.  There are 20 flavors of ace-cream, and then 15 choices of topping. Assuming you must choose 1 flavor of ice cream and 1 topping as the question implies, there are then 4*3*20*15 = 3600 different combinations to choose from. Answer is D: 3600

The reporter forgot to multiply the decimal by 100, making it 25%