conversations.from: human
conversations.value: I need help with this problem:
  There were 80 cars in a parking lot. At lunchtime, 13 cars left the parking lot but 5 more cars went in than left. How many cars are in the parking lot now?
conversations.from: assistant
conversations.value: There are 80 - 13 = 67 cars in the parking lot after 13 went out.
  13 + 5 = 18 cars went in the parking lot at lunchtime.
  So, there are 67 + 18 = 85 cars in the parking lot now.