Question 1025688
<pre>
             rate            time         distance

DOWN         r+1.8          {{{2&24/60}}}         43.2

UP           r-1.8            t            43.2
</pre>


The DOWN part lets you find the unknown r, speed of the motorboat if no current.  The UP part lets you find the asked time,  {{{t=43.2/(r-1.8)}}}.