conversations.from: human
conversations.value: Timothy has three times the number of pens that George owns. Sarah has half as many pens as Timothy. If George has 18 pens, how many pens does Sarah have?
  Solve this problem.
conversations.from: assistant
conversations.value: Timothy has 18 * 3 = 54 pens.
  This means that Sarah has 54 /2 = 27 pens.