# SOLUTION: I am having a difficult time with this problem. Rita rows 12 km upstream and 12 km downstream in 3 hours. The speed of her boat in still water is 9 km/hr. Find the speed of the str

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 Question 69986: I am having a difficult time with this problem. Rita rows 12 km upstream and 12 km downstream in 3 hours. The speed of her boat in still water is 9 km/hr. Find the speed of the stream. Someone please help?Answer by ankor@dixie-net.com(15657)   (Show Source): You can put this solution on YOUR website!I am having a difficulty time with this problem. Rita rows 12 km upstream and 12 km downstream in 3 hours. The speed of her boat in still water is 9 km/hr. Find the speed of the stream. : let x = speed of the stream: : Speed upstream = (9-x) Speed downstream = (9+x) : Time = dist/speed : Time upstream + time downstream = 3 hrs : = 3 : Multiply equation by (9-x)(9+x), results : 12(9+x) + 12(9-x) = 3(9-x)(9+x) : 108 + 12x + 108 - 12x = 3(81 - x^2); difference of squares : 216 = 243 - 3x^2; 12x's eliminated : 0 = 243 - 216 - 3x^2 : +3x^2 = 243 - 216 : 3x^2 = 27 : x^2 = 27/3 : x^2 = 9 : x = SqRt(9) : x = 3 mph speed of the stream : : Check our solution: speed up is 6, speed down is 12 12/12 + 12/6 = 3 hrs : Did this make sense to you?