Question 1142022
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<pre>
The time equation for this kinematic problem is this


    {{{55/(x+4)}}} = {{{33/(x-4)}}}.


where x is the speed at no wind, in miles per hour.


To solve the equation, cross-multiply


    57*(x-4) = 33*(x+4),


simplify and get


    57x - 33x = 33*4 + 57*4

    x = {{{(33*4 + 57*4)/(57-33)}}} = 15 miles per hour.     <U>ANSWER</U>
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