Question 1122402
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<U>Selma</U>      <U>Trudy</U>

12 + x/5 = 18 + x/7    (x = amount of time, in minutes)


x/5 - x/7 = 18 - 12


{{{(7x)/35}}} - {{{(5x)/35}}} = 6


{{{(2x)/35))}}} = 6  ====>  x = {{{(35*6)/2}}} = 105 minutes.


<U>Answer</U>.  105 minutes,  or 1 hour and 45 minutes.
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<U>Another solution using fingers</U>


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Every 35 minutes Selma packs 7 boxes, while Trudy packs 5 boxes.

Thus every 35 minutes Selma decreases the difference between them in 2 boxes.


Since the original difference was 6 boxes, Selma needs 3 times 35 minutes, or 105 minutes, in all, to catch Trudy.
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