Question 1053938
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Debra's boat has a top speed of 6 miles per hour in still water. While traveling on a river at top speed, 
she went 10 miles upstream in the same amount of time she went 30 miles downstream. Find the rate of the river current. 
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Your governing equation is "time" equation

{{{10/(6-v)}}} = {{{30/(6+v)}}}.

Here the left side is the time for travel 10 miles upstream at the speed (6-v) mph, where v is the current speed.

The right side is the time for travel 30 miles downstream at the speed (6+v) mph.

To solve the equation, multiply both sides by (6-v)*(6+v). You will get

10*(6+v) = 30*(6-v),  or

60 + 10v = 180 -30v,  or

40v = 120  --->  v = {{{120/40}}} = 3.

<U>Answer</U>.  The rate of the river current is 3 mph.
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