The number of combinations is
There are 5 men on a basketball team, and the coach has his choice of 15 men. There is no definition given of the position each man will be playing nor the relative importance of each player such as captain or forward.
This means we are working with a "combination" of
Our possibilities start with
But as we add players to the team, we also reduce the number of positions left, so as each player is added to the team our possibilities are further reduced:
the combination looks like