Please help with the attached file.

Here is what we started off with in class, but I have NO CLUE where to go from here...this is one of the first homeworks that I am having difficulty with, and if someone can help me out...it would be greatly appreciated!

Thanks!

Code:int fac(int z) { int i; int res =1; for(i=1; i<=z; i++){ res = res * i; } return res; } int select(int n, int k) { return fac(n)/(fac(k)*fac(n-k)); }