I am having a problem with one of my assignments for my class, and for the life of me, I cannot solve it. Any help would be much appreciated!

Here it is:

A committee of four is to be selected from a group of 15 people. How many different committees are possible if one person is the chair, and the rest are general member?

1365 is the number of "general" committees, not considering who is the "chair." If we take any one committee of 4, then there are 4 ways in which 1 of them can be the chair, and the rest are just part of the committee.