prep里一个数学题

jess77

A hiker walking at a constant rate of 4 mile per hour is passed by a cyclist traveling in the same direction along the same direction along the same path at a constant rate of 20 miles per hour.
The cyclist stops to wait for the hiker 5 minutes after passing her, while the hiker continues to walk at her constant rate. How many minutes must the cyclist wait until the hiker catches up?

我算出来是25，不知道为什么答案是20呢？

quellekind

that hiker is still hiking during that 5 min, you must forget count it in.

jess77

晕死~  对，没错，谢谢！