Question 922685
a boat travels 45 mi upstream (against the current) in 5h. The boat travels the same distance downstream in 3h. What is the rate of the current?
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let x=rate of boat in still water
let c=rate of current
(x+c)=rate of boat downstream
(x-c)=rate of boat upstream
distance/rate=travel time
45/(x-c)=5
45/(x+c)=3
..
5x-5c=45
3x+3c=45
..
15x-15c=135 (mult. eq by 3)
15x+15c=225 (mult. eq by 5)
subtract:
-30c=-90
c=3
What is the rate of the current? 3 mph