Question 1192778
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The first man walks 3 km/h for 3 hours before the second man starts, traveling a distance of 3*3=9km.<br>
The rate at which the second man overtakes the first man is the difference in their walking rates, which is 1km/h.<br>
To make up a distance of 9km at a rate of 1km/h takes 9/1=9 hours.<br>
In 9 hours the second man walks 9*4=36km.  (And the first man by then has walked 12*3=36km.)<br>
ANSWER: The second man walks 36km before he overtakes the first man.<br>