conversations.from: human
conversations.value: John buys a box of 40 light bulbs.  He uses 16 of them and then gives half of what is left to a friend.  How many does he have left?
  Can you solve this problem?
conversations.from: assistant
conversations.value: He had 40-16=24 left after using some
  Then after giving some away he is left with 24/2=12