SOLUTION: the rate of the boat in still water is 8 mph. At this rate a 30 mile trip downstream takes the same amount of time as an 18 mile trip upstream. What is the rate of the current?

Question 518231: the rate of the boat in still water is 8 mph. At this rate a 30 mile trip downstream takes the same amount of time as an 18 mile trip upstream. What is the rate of the current?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = rate in still water
Let = rate of current
going downstream:
(1)
Going upstream:
(2)
-----------------
given:
mi
mi
mi/hr
---------------
(1)
(2)
-----------------
(1)
(2)
Add the equations

hrs
and, since
(1)
(1)
(1)
(1)
The rate of the current is 2 mi/hr
check:
(1)
(1)
(1)
OK
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