conversations.from: human
conversations.value: Tom's ship can travel at 10 miles per hour.  He is sailing from 1 to 4 PM.  He then travels back at a rate of 6 mph.  How long does it take him to get back?
  Work out the solution step by step.
conversations.from: assistant
conversations.value: He was travelling at full speed for 4-1=3 hours
  So he went 3*10=30 miles
  That means it takes 30/6=5 hours to get back