conversations.from: human
conversations.value: While playing with her friends in their school playground, Katelyn saw 50 fairies flying above the nearby forest. After about twenty minutes, one of her friends saw half as many fairies as Katelyn saw come from the east and join the fairies that were there. Ten minutes later, 30 fairies flew away. How many fairies are remaining?
  Find the solution.
conversations.from: assistant
conversations.value: Katelyn's friend saw 1/2*50 = 25, half as many fairies as Katelyn initially saw
  The total number of fairies flying above the forest now is 50 + 25 = 75
  If thirty fairies then flew away, there were 75 - 30 = 45 fairies that remained.