Let v be the speed of the boat in still water, in miles per hour.


Then the effective rate traveling downstream is (v+5) mph;

     the effective rate traveling upstream   is (v-5) mph.


The "time" equation is

     = ,

according to the condition.


To solve it, cancel the factor 44 in both side, first. You will get

     = .


Cross multiply and simplify

    2*(v-5) = v+5

    2v - 10 = v + 5

    v = 15.


ANSWER.  The boat rate in still water is 15 miles per hour.