The manager of an accounting department wants to form a three-person advisory committee from the 20 employees

Question:

The manager of an accounting department wants to form a three-person advisory committee from the 20 employees in the department. In how many ways can the manager form this committee?
a. Identify the number of objects in the group n and the number of objects r to be selected.
b. Evaluate nCr.
c. Write the result as a sentence.