Question 757600
Two persons are to run a race, but one can run 11 meters per second,
 whereas the other can run 7 meters per second.
 If the slower runner has a 42-meter head start, how long will it be
 before the faster runner catches the slower runner, if they begin
 at the same time?
:
We can us relative speed here which is 11 - 7 = 4 m/sec
How long would it take to cover 42 meters at this speed
:
{{{42/4}}} = 10.5 sec
:
:
You can confirm this for yourself, find the distance traveded
10.5 * 11 = 115.5 m
10.5 * 7  =  73.5 m
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the difference: 42 m