Help please....

Answer the questions below. (If necessary, consult a list of formulas.) (a) A company that makes crayons is trying to decide which 4 colors to include in a promotional mini-box of 4 crayons. The company can choose the 4 mini-box colors from its collection of 65 colors. How many mini-boxes are possible? [I] (b) A company has 38 salespeople. A board member at the company asks for a list of the top 4 salespeople, ranked in order of effectiveness. How many such rankings are possible? D