When you normally drive the freeway between Sacramento and San Francisco at an average speed of 100 km/hr (62.1 mph ), the trip takes 1.00 hr and 24.0 min. On a Friday afternoon, however, heavy traffic slows you down to an average of 65.0 km/hr (40.4 mph ) for the same distance.

How much longer does the trip take on Friday than on the other days?