Question 1193694
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The number of 40 has two divisors, 10 and 2, that differ by 8 units and such that if you divide 40 by 10 one time


and divide 40 by 2 next time, you will get two quotients, 4 and 20, that differ exactly 16 units.


By making this mental thought experiment, you quickly will get the answer to your question, without using any equations and much faster.


<U>ANSWER</U>.  The slower rate is 2 miles per hour.
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Solved.


Good as a mental exercise . . .