Question 213073
 mark leaves the house for school walking at the rate of 4kph. two hours later jane follows mark at a walking rate of 6kph. how long will jane have to walk to overtake mark?
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In 2 hours, Mark is 8 km away.  Jane gains on him, or closes, at 2 kph (6-4).
It will take her 4 hours to overtake him (8/2).