SOLUTION: Ben's boat will take 1½ hours longer to go 12 miles up a river than to return. What is the rate of his boat if the rate of the current is 2 miles an hour?
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Question 458154: Ben's boat will take 1½ hours longer to go 12 miles up a river than to return. What is the rate of his boat if the rate of the current is 2 miles an hour?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
The basic formula is distance equals rate times time.
Downstream trip. 12 miles distance, the rate 
of the boat PLUS 2 mph, 
hours time.
t)
Solve for
Upstream trip. Same 12 miles, the rate of the boat MINUS 2 mph, the time it took to go downstream PLUS 1.5 hours.
(t\ +\ 1.5))
Solve for
Apply the LCD:
}{r\ -\ 2})
Now we have two expressions for , one describing the upstream trip and one describing the downstream trip. Since 
, we can say:
}{r\ -\ 2}\ =\ \frac{12}{r\ +\ 2})
Now all you need to do is cross-multiply, collect like terms, and solve for
John
My calculator said it, I believe it, that settles it
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