Mr. Parker's job is on a curvy side road next to a highway exit. He drives down the highway at 60 m.p.h., and at this rate he always gets to work at 7:30 a.m. However, at 7:15 because of a detour sign, he was forced to leave the highway and take the side road, driving at a steady speed of 40 m.p.h. for the rest of the way. He arrived at work15 minutes later than originally planned.