SOLUTION: Mike and his brothers can row a boat 18 km per hour in still water. It takes them as long to row 14 km downstream and 10 km upstream. Find the speed of the stream.

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Question 1144501: Mike and his brothers can row a boat 18 km per hour in still water. It takes them as long to row 14 km downstream and 10 km upstream. Find the speed of the stream.
Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
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Let x be the speed of the stream


Then  the speed rowing downstream is  (18+x) km/h, 

while the speed rowing   upstream is  (18-x) km/h.


The time rowing 14 kilometers downstream is  14%2F%2818%2Bx%29  hours;

the time rowing 10 kilometers  upstream is  10%2F%2818-x%29  hours.


It gives you the equation


    14%2F%2818%2Bx%29  = 10%2F%2818-x%29.


To solve it, multiply both sides by (18+x)*(18-x).  You will get


    14*(18-x) = 10*(18+x)

    14*18 - 14x = 10*18 + 10x

     14*18 - 10*18 = 10x + 14x

     4*18          = 24x

     x             = %284%2A18%29%2F24 = 3.


ANSWER.  The rate of the stream is 3 kilometers per hour.

Solved.