Question 324804
Rate*Time=Distance
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Let B be the barge speed in still water.
{{{(B+3)3=27}}}
{{{B+3=9}}}
{{{B=6}}}
On the return trip, the current works against you.
{{{(B-3)T=27}}}
{{{6-3)T=27}}}
{{{3T=27}}}
{{{T=9}}}
It takes 9 hours to make the return trip.