SOLUTION: The speed of a stream is 5 mph. A boat travels 7 miles upstream in the same time it takes to travel 17 miles downstream. What is the speed of the boat in still​ water?

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Question 1127384: The speed of a stream is 5 mph. A boat travels 7 miles upstream in the same time it takes to travel 17 miles downstream. What is the speed of the boat in still​ water?
Found 2 solutions by ikleyn, 4198181:
Answer by ikleyn(52817) About Me  (Show Source):
You can put this solution on YOUR website!
.
The time equation is


    7%2F%28x-5%29 = 17%2F%28x%2B5%29.


    7*(x+5) = 17*(x-5)

    7x +35 = 17x - 85

    35 + 85 = 17x - 7x

    120 = 10x

    x = 120/10 = 12.


Answer.  The speed of the boat in still water is 12 miles per hour.

Solved.


Answer by 4198181(13) About Me  (Show Source):
You can put this solution on YOUR website!
Obviously the boat can move itself so to find how fast it moves in still water we would do 17-5 because 5 miles is how far it can move without propelling itself and 17 miles is how far the boat can propel itself and the river will move it. 17-5 is 12 so the speed of the boat in still water is 12mph