Question 739883
A barge can travel 45 miles downstream in the same time it takes to travel 30 miles upstream. If the speed of the barge in still water is 15 miles per hour, what is the speed of the current?
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let x=speed of current
15+x=speed of barge downstream
15-x=speed of barge upstream
travel time=distance/speed (same both ways)
..
{{{45/(15+x)=30/(15-x)}}}
{{{45(15-x)=30(15+x)}}}
{{{675-45x=450+30x}}}
75x=225
x=3
speed of current=3 mph