A cyclist rides a bicycle over a route which is 1/3 uphill…

A cyclist rides a bicycle over a route which is 1/3 uphill, 1/3 level, and 1/3 downhill. If the cyclist covers the uphill part of the route at the rate of 14 km per hour and the level part at the rate of 21 km per hour, what rate in km per hour would the cyclist have to travel the downhill part of the route in order to average 21 km per hour for the entire route?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #18182