SOLUTION: Aubry's boat goes 20 mph in still water. It travels 75 miles upstream and back in a total time of 8 hours. What is the speed of the current?

Question 132577: Aubry's boat goes 20 mph in still water. It travels 75 miles upstream and back in a total time of 8 hours. What is the speed of the current?
Answer by mathispowerful(115) (Show Source): You can put this solution on YOUR website!
Since total time is 8 hours:

If we let x be the current speed, the upstream speed is
20-x, downstream speed is 20+x
So
Multiply (20-x)(20+x) on both sides:
75(20+x)+75(20-x)=8(20-x)(20+x)
simplify it we get:

That is

x=5
So the answer is 5 miles/hr.
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