SOLUTION: "It took Emily 25 min to ride her bicycle to the repair shop and 1h 15 min to walk back home. If Emily can ride her bicycle 8 km/h faster than she can walk, how far is the repair s

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: "It took Emily 25 min to ride her bicycle to the repair shop and 1h 15 min to walk back home. If Emily can ride her bicycle 8 km/h faster than she can walk, how far is the repair s      Log On


   



Question 1160587: "It took Emily 25 min to ride her bicycle to the repair shop and 1h 15 min to walk back home. If Emily can ride her bicycle 8 km/h faster than she can walk, how far is the repair shop from her house?"


Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
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Let "w" be her rate walking, in km/h.

Then the biking rate is (w+8) km/h.


From the condition you have this equation


    %2825%2F60%29%2A%28w%2B8%29 = %2875%2F60%29%2Aw


saying that the distance is the same in both directions.


From the equation (canceling 60 in the denominators)


    25*(w+8) = 75w

    w + 8 = 3w

    8 = 3w - w = 2w

    w = 8/2 = 4 km/h.


So, the walking rate is 4 km/h;  then the (walking) distance is  %285%2F4%29%2A4 = 5 kilometres.    ANSWER

Another solution

Let "d" be the distance under the question.


Then from condition you have this equation, connecting rates


    d%2F25 - d%2F75 = 8%2F60  kilometres per minute.


Simplify by canceling factor 5 in denominators

    d%2F5 - d%2F15 = 8%2F12 = 2%2F3.


Multiply both sides by 15


    3d - d = 10

    2d     = 10

     d     = 10/2 = 5 kilometres,


and you get the same answer for the distance.

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Solved two times by different methods for your better understanding.