Question 1159231
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Let r be his rate in still water.


Then the rate downstream is (r+2) km/h; while the rate upstream is (r-2) km/h.


The time to travel 5 km downstream is  {{{5/(r+2)}}};  The time to travel 5 kn upstream is  {{{5/(r-2)}}}.


Now your equation becomes


    {{{5/(r-2)}}} = {{{2*(5/(r+2))}}}.


To solve it, cross multiply


    5*(r+2) = 2*5*(r-2).


Simplify and solve

    5r + 10 = 10r - 20

    10 + 20 = 10r - 5r

    30      = 5r

     r      = 30/5 = 6.


<U>ANSWER</U>.  Ed's rate in still water is 6 km/h.
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Solved.