Every day a man meets his wife at the train station after work, and she drives him home. She always arrives exactly on time. One day he catches an earlier train and arrives an hour early. He immediately begins walking home along the same route they usually drive. Eventually his wife sees him on her way to the station and drives him the rest of the way home. When they arrive home the man notices that they arrived 20 minutes earlier than usual. How much time did the man spend walking?
(man time walking) + (man riding with wife time) = 40 minutes. Without the distance of the commute or relative speeds of the two modes of transportation I can't figure this out.
