SOLUTION: The Speed of a river is 7mph. If a boat travels 20 miles downstream in the same time it takes to travel 10 miles upstream, find the speed of the boat in still water?

Question 804041: The Speed of a river is 7mph. If a boat travels 20 miles downstream in the same time it takes to travel 10 miles upstream, find the speed of the boat in still water?

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the time in hours going both
upstream and downstream
Let = the speed of the boat in still water
-----------------
Going downstream:
(1)
Going upstream:
(2)
--------------------
(1)
and
(2)
-------------------
Subtract (2) from (1)
(1)
(2)

-----------
(1)
(1)
(1)
(1)
(1)
The speed of the boat in still water is 21 mi/hr
check:
(2)
(2)
(2)
(2)
OK

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