SOLUTION: River is running at 2 km/hr.It takes a man twice as long to row up as to row down the river.What is the rate of the man in still water?

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Question 867972: River is running at 2 km/hr.It takes a man twice as long to row up as to row down the river.What is the rate of the man in still water?
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
Let r = the man's rate in still water. His rate downstream is r+2 km/hr and his rate upstream is r-2 km/hr. The problem description forces the reader to infer that the time quantity described is for a specific distance. This is a fault in the given problem description, but would be a very likely meaning.

______________rate__________time__________distance
DOWN__________r+2___________t______________d
UP____________r-2___________2t_____________d

BEFORE DOING THE ALGEBRA STEPS, I THOUGHT: At best, you will have one equation and still two unknown variables.

BUT AFTER DOING THESE STEPS:
%28r%2B2%29t=%28r-2%29%2A2t
rt%2B2t=2rt-4t
rt-2rt=-4t-2t
-rt=-6t
highlight%28r=6%29