conversations.from: human
conversations.value: 9 years from now, John will be 3 times as old as he was 11 years ago. How old is he now?
  Work out the solution step by step.
conversations.from: assistant
conversations.value: Let J represent John’s age.
  We have J + 9 = 3(j − 11)
  So, J + 9 = 3J − 33
  So, 9 = 2J − 33
  So, 42 = 2J
  Which means that John’s age is J = 42 / 2 = 21