Question 3
Walter has two options when going to school. He can (a) walk 3 minutes to the bus stop and then ride the bus for 15 minutes to the school, or (b) walk 5 minutes to the subway stop and then ride the subway for 6 minutes and walk 5 minutes to school. If he does not have to wait for the bus at the bus stop, nor the train on the subway station, what is the minimum number of minutes required for him to get to school?