Serge’s outgoing 115-kilometer bike involved riding uphill for 2 hours and on level ground for 3
hours. On the return trip, on a different 135-kilometer trail, he rode downhill for 2 hours and on
level ground for 3 hours. Determine Serge’s three speeds if his speed on level ground is the
average of his uphill and downhill speeds.
speed = distance/time, so
uphill: 115/3
downhill: 135/2
average: (115/3 + 135/2)/2