SOLUTION: A boy rows a boat against a stream flowing at 2 kmph for a distance of 9 km,and then turns round and rows back with the current. If the whole trip occupies 6 hours, find the boys

Question 902945: A boy rows a boat against a stream flowing at 2 kmph for a distance of 9 km,and then turns round and rows back with the current. If the whole trip occupies 6 hours, find the boys rowing speed in still water.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
A boy rows a boat against a stream flowing at 2 kmph for a distance of 9 km,and then turns round and rows back with the current. If the whole trip occupies 6 hours, find the boys rowing speed in still water.
***
let x=speed of boat in still water
x+2=speed of boat downstream
x-2=speed of boat upstream
travel time=distance/speed
9/(x+2)+9/(x-2)=6
lcd:(x+2)(x-2)
9(x-2)+9(x+2)=6(x^2-4)
9x-18+9x+18=6x^2-24
6x^2-18x-24=0
x^2-3x-4=0
(x-4)(x+1)=0
x=4
Boys rowing speed in still water=4 kmph

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