A walks at 30 kmph and 30 hours after his start, B cycles after him at 40 kmph. How far from the start does B catch up with A?
Choices:
A) 1200km B) 1500km C) 2000km D) 2500km E) 3600km
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 30 hours.   x/30 - x/40 = 30   x = 3600 km   Answer is 2500km
<result>D</result>
A walks at 30 kmph and 30 hours after his start, B cycles after him at 40 kmph. How far from the start does B catch up with A?