Allen, Benedict and Carl started at the same instant from the same point using the
same route trying to overtake a fourth cyclist Donald traveling at a constant speed ahead of them. Allen and Benedict each took 10 hours and 2 hours respectively to overtake Donald.
Given that Allen, Benedict and Carl each cycled at the constant speed of 4 km/h, 5 km/h and 10 km/h respectively throughout the journey, find the time, in hours, that Carl took to overtake Donald..

En ? are you sure the data are correct ?.

2/5 hours.

would u pls offer more informations of your solution? thanks..