<PRE><B>Question 926695</B>
x = speed of boat in still water
s = d/t
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downstream:
x + 6 = 9/t
t = 9/(x + 6)
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upstream:
x - 6 = 3/t
t = 3/(x - 6)
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9/(x + 6) = 3/(x - 6)
9(x - 6) = 3(x + 6)
9x - 54 = 3x + 18
6x = 72
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answer:
x = speed of boat in still water = 12 mph
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