SOLUTION: A motorboat takes 5 hours to travel 200km going upstream. The return trip takes 4 hours going downstream. What is the rate of the boat in still water and what is the rate of the cu

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Question 969453: A motorboat takes 5 hours to travel 200km going upstream. The return trip takes 4 hours going downstream. What is the rate of the boat in still water and what is the rate of the current?
Answer by lwsshak3(11628) About Me  (Show Source):
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A motorboat takes 5 hours to travel 200km going upstream. The return trip takes 4 hours going downstream. What is the rate of the boat in still water and 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
travel time *rate=distance
..
5(x-c)=200
4(x+c)=200
..
5x-5c=200
4x+4c=200
..
20x-20c=800
20x+20c=1000
add:
40x=1800
x=45
subtract:
40c=200
c=5
rate of boat in still water=45 km/hr
rate of current=5 km/hr