Answer the following question, with explanation first.
Reese has been practicing piano for four hours every week. How many hours will he practice after five months?

80
If Reese practices 4 four hours every week, in a month, with four weeks, he would have practiced for 4 * 4 = 16 hours.

In five months, Reese would have practiced for 5 * 16 = 80 hours.

.

Thus, the answer is 80