SOLUTION: Denmark bikes the 36km to the resort averaging a certain speed. the return trip is made at a speed 3kph slower. the total time for the roundtrip is 7 hours. find Denmark's averagde

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Question 1119567: Denmark bikes the 36km to the resort averaging a certain speed. the return trip is made at a speed 3kph slower. the total time for the roundtrip is 7 hours. find Denmark's averagde speed on each part of the trip.
Answer by ikleyn(52818)   (Show Source): You can put this solution on YOUR website!
.
Let x be the slower speed in kilometers per hour.

Then the faster speed is (x+3) km/h.


The time equation is 


 +  = 7.    ( <<<---=== each fraction in the left side is the time, spent to cover 36 kilometers 
                                with the corresponding speed).


To solve it, multiply both sides by x*(x+3); then simplify and solve the quadratic equation.


Answer.  The slower speed is 9 km/h; the faster speed is 12 km/h.


Check.    +  = 4 + 3 = 7 hours.

Solved.


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