Question 1120738
<pre>
                SPEED        TIME    DISTANCE

downstream        r+c          4       24

upstream         2r-c          4       24
</pre>

{{{system(4(r+c)=24,4(2r-c)=24)}}}

-

{{{system(r+c=6,2r-c=6)}}}


{{{3r=12}}}


{{{highlight(r=4)}}}-------boat, downstream speed
-
{{{highlight(c=2)}}}-------current