text: # Kinematics boat question
  
  ## Main Question or Discussion Point
  
  a boat takes 3.1 hours to travel 15 km down a river, then takes 5.1 hours to travel the same distance upstream. how fast is the river traveling.
  
  I found the boat is traveling at 4.84km/hr down the stream and 2.94 km/hr up it. not sure where to go next.
  
  Any help would be appreciated.
  
  ## Answers and Replies
  
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  phinds
  Science Advisor
  Gold Member
  2019 Award
  d=rt
  
  Let's say the river's speed is 1 kph and the boat's speed is 2 kph then the boat will travel downstream at 3 kph and upstream at 1 kph. So when you go downstream you add the speeds, but when going upstream, you subtract the river's speed from the boat's speed. Try working that backwards.
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