conversations.from: human
conversations.value: Tom needs to lower a rope down 6 stories.   One story is 10 feet.  The only rope being sold is 20 feet long but you lose 25% when lashing them together.  How many pieces of rope will he need to buy?
conversations.from: assistant
conversations.value: He needs 10*6=60 feet
  He loses 20*.25=5 feet each time
  So he gets 20-5=15 feet from each piece
  That means he needs 60/15=4 pieces of rope