SOLUTION: The river is moving at 5 miles per hour. A boat can travel 5 miles upstream in the same time that it takes to travel 15 miles downstream. How fast can the boat go in still water?

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Question 402051: The river is moving at 5 miles per hour. A boat can travel 5 miles upstream in the same time that it takes to travel 15 miles downstream. How fast can the boat go in still water?
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
5%2F%28r+-+5%29+=+15%2F%28r%2B5%29
==> 1%2F%28r+-+5%29+=+3%2F%28r%2B5%29
==> r + 5 = 3(r-5)
==> r + 5 = 3r - 15
==> 20 = 2r
==> r = 10 mph, the speed of the boat in still water.