conversations.from: human
conversations.value: A bag of buttons had 21 buttons in it. Seven buttons had two holes and the rest had four holes. How many holes were in all the buttons in the bag?
  Work out the solution step by step.
conversations.from: assistant
conversations.value: There were 21 - 7 = 14 buttons with four holes.
  The four-holed buttons had 14 * 4 = 56 holes.
  The two-holed buttons had 7 * 2 = 14 holes.
  Thus, there were 56 + 14 = 70 holes in all the buttons in the bag.