SOLUTION: The speed of a stream is 4 km/h. A boat travels 6 km upstream in the same time it takes to travel 12 km downstream. What is the speed of the boat in still water?

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Question 318343: The speed of a stream is 4 km/h. A boat travels 6 km upstream in the same time it takes to travel 12 km downstream. What is the speed of the boat in still water?
Answer by nyc_function(2741) About Me  (Show Source):
You can put this solution on YOUR website!
6 km × 1 hour/(b-4 km) = 12 km × (1 hour/(b+4 km)
6/(b-4) hours = 12/(b+4) hours
6(b+4) = 12(b-4)
6b + 24 = 12b - 48
72 = 6b
b = 12
The boat's speed in still water is 12 km/hour.