Question 1127535
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Let x = "how fast is Tracy jogging".


Then Joe' speed in still water is the same x miles per hour, according to the condition,
and Joe's effective speed paddling against the current is (x-2) miles per hour.


Then the time equation is

{{{6/(x-2)}}} - {{{6/x}}} = 1 hour.


Thus the setup is done.


To solve equation, start multiplying both sides by x*(x-2).


6x - 6(x-2) = x*(x-2)


x^2 - 2x - 12 = 0


{{{x[1,2]}}} = {{{(2 +- sqrt(2^2 +4*12))/2}}} = {{{(2 +- sqrt(52))/2}}} = {{{1 +- sqrt(13)}}}.


The positive root  {{{1 + sqrt(13)}}} = 4.605 mph is the solution. 


<U>Check</U>.  {{{6/(4.605-2)}}} - {{{6/4.605}}} = 1.000   ! Correct !
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