Question 1047302
Trip took how many hour?  Omitted.  Let this be T.
Unknown distance each way may be d.

<pre>
               SPEED         TIME            DISTANCE

UPSTREAM         5           {{{(d/5)}}}            d

DOWNSTREAM       11          {{{(d/11)}}}           d

Total                        T               2d
</pre>


{{{11d/55+5d/55=T}}}

{{{d(11+5)/55=T}}}

{{{d(16/55)=T}}}

{{{d=(55/16)T}}}


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Did you mean, "...the entire trip took FOUR hours." ?  In that case, you would have T=4, and you can then evaluate d.