Question 835134
Harry's motorboat can make an average of 8 miles per hour. One day he sets out for a trip, only to have the motor break down. Harry rows back at two miles an hour. When he reaches his dock, he finds that he has been gone 5 hours. How far has he rowed?
<pre>
Let D = the distance he motored out = the distance he rowed back.


               Distance     Rate    Time=Distance/Rate
Motoring out      D          8            D/8
Rowing back       D          2            D/2
------------------------------------------------------
                            Total Time =   5

Time motoring out + Time rowing back = 5 hours

{{{D/8}}}{{{""+""}}}{{{D/2}}} {{{""=""}}} {{{5}}}

Multiply through by 8

         D + 4D = 40
             5D = 40
              D = 8 miles

Edwin</pre>