Question 1108152
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{{{100/r}}} - {{{100/(r+5)}}} = 1   is your time equation  (two fractions are values of time spent under each scenario)

where "r" is the unknown rate under the question.


To solve it, multiply both sides by r*(r+5). You will get


100*(r+5) - 100r = r*(r+5)

100r + 500 - 100r = r^2 + 5r

r^2 + 5r - 500 = 0.

(r-20)*(r+25) = 0.


Only the positive root r = 20  makes sense.


<U>Answer</U>.  The rate under the question is 20 miles per hour.
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