Answer:
Step-by-step explanation:
For this problem you have to use combinations. from 10 choices you are choosing 3. This means you are doing 10 choose 3. If you don't know what choose is I can explain.
Any number x choose y is the same as (x factorial)/(y factorial)(x-y factorial).
In this case that is 10 factorial/3 factorial times 7 factorial. ten factorial is the same as 10*9*8*7 factorial. So in the original equation you can factor away the seven factorials to get 10*9*8/3*2*1 factoring again you get 10*3*4 which is 120.
