SOLUTION: A boat can travel on a river 7 miles upstream in the same time it takes to travel 9 miles downstream. Find the speed of the current if the speed of the boat in still water is 8 mil

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Question 829352: A boat can travel on a river 7 miles upstream in the same time it takes to travel 9 miles downstream. Find the speed of the current if the speed of the boat in still water is 8 miles per hour.
Answer by TimothyLamb(4379) (Show Source):
You can put this solution on YOUR website!
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x = boat speed
y = current speed
x = 8 mph
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s = d/t
t = d/s
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t = 7/(x - y)
t = 9/(x + y)
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7/(x - y) = 9/(x + y)
7(x + y) = 9(x - y)
7x + 7y = 9x - 9y
9y + 7y = 9x - 7x
16y = 2x
y = 2x/16
y = (2*8)/16
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y = current speed = 1 mph
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