Find how many 5-player teams could be made out of group 7 people:
- if the captain is already selected (from the same group of 7 people)
So, I know that I have to use: $_{n}C_{k} = \frac{n!}{k!(n-k)!}$, to find all the combinations of $n$ items, selected $k$ at a time.
I can't seem to figure out the implication of the captain (pre)selection, i.e. how are $n$ and $k$ affected by the above constraint?
Every useful advice will be appreciated!