A walks at 30 kmph and 30 hours after his start, B cycles after him at 50 kmph. How far from the start does B catch up with A?	Choose the correct option.
A) 1200km  B) 1500km  C) 2000km  D) 2250km  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/50 = 30   x = 2250 km   Answer is 2250km
<result>D</result>
A walks at 30 kmph and 30 hours after his start, B cycles after him at 50 kmph. How far from the start does B catch up with A?