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Going downstream the beaver swims 4 times as fast as he does swimming upstream, thus \[b + s = 4(b  s).\] What is the relationship between $b$ and $s?$ Penny
Simplify the expression \[b + s = 4(b  s)\] to find a relationship between $b$ and $s.$ What did you get? Penny
The question is "How many times faster is its speed in still water than the speed of the stream?" The speed in still water is $b$ and the speed of the stream is $s$ so the question is " Find the number $k$ so that $b = k \times s.$ What is $k?$" Penny
 


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