Question 1127536
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<pre>
Let x = Jon's speed in still water.


Then the time equation, from the condition, is


{{{5/(x+1)}}} + {{{6/(x-1)}}} = 3   hours.


Solve it for x.


To start, multiply all the terms by (x-1)*(x+1).
</pre>


<U>Answer</U>.  &nbsp;&nbsp;x, &nbsp;or Jon' speed in still water, is &nbsp;4 &nbsp;km/h.