conversations.from: human
conversations.value: I would love to understand how to solve this problem: David finished his homework in 60 minutes. He spent 15 minutes on his math homework and 18 minutes on his spelling homework. He spent the rest of the time reading for his daily reading log. How many minutes did he spend reading?
  Can you explain?
conversations.from: assistant
conversations.value: He spent 15 + 18 = 33 minutes doing homework.
  David spent 60 - 33 = 27 minutes reading.