A walks at 10 kmph and 7 hours after his start, B cycles after him at 20 kmph. How far from the start does B catch up with A?	Answers.
A) 100km B) 140km C) 50km D) 120km E) 200km
Suppose after x km from the start B catches up with A. Then, the difference in the time taken by A to cover x km and that taken by B to cover x km is 7 hours.   x/10 - x/20 = 7   x = 140 km   Answer is 140km
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A walks at 10 kmph and 7 hours after his start, B cycles after him at 20 kmph. How far from the start does B catch up with A?