SOLUTION: A paddle boat can move at a speed of 2 ​km/h in still water. The boat is paddled 14 km downstream in a river in the same time it takes to go 7 km upstream. What is the sp

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Question 1056020: A paddle boat can move at a speed of 2 ​km/h in still water. The boat is paddled 14

km downstream in a river in the same time it takes to go 7 km upstream. What is the speed of the​ river?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
system%28r=2%2Cd=14%2Cu=7%2Ct=unknownTimeBothDirections%2Cc=unknownRiverCurrentSpeed%29 
                  SPEED      TIME     DISTANCE
DOWNSTREAM         r+c        t        d
UPSTREAM           r-c        t        u

system%28t=d%2F%28r%2Bc%29%2Cand%2Ct=u%2F%28r-c%29%29

d%2F%28r%2Bc%29=u%2F%28r-c%29

d%28r-c%29=u%28r%2Bc%29

dr-dc=ur%2Buc

dr-ur=uc%2Bdc

dr-ur=%28u%2Bd%29c

highlight%28%28dr-ur%29%2F%28u%2Bd%29=c%29

Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!

A paddle boat can move at a speed of 2 ​km/h in still water. The boat is paddled 14

km downstream in a river in the same time it takes to go 7 km upstream. What is the speed of the​ river?
Let speed of the current be C

We then get: 14%2F%282+%2B+C%29+=+7%2F%282+-+C%29

14(2 - C) = 7(2 + C) ------- Cross-multiplying

28 – 14C = 14 + 7C

– 14C – 7C = 14 – 28 

– 21C = - 14

C, or rate of current =