conversations.from: human
conversations.value: It takes 7 years for an apple tree to bear fruit. If Lydia planted a tree when she was 4 years old and is now 9 years old, how old would she be when she gets to eat an apple from her tree for the first time?
  Work out the solution step by step.
conversations.from: assistant
conversations.value: The tree has been planted for 9 - 4 = 5 years
  It will take another 7 - 5 = 2 years for it to bear fruit
  Lydia will be 9 + 2 = 11 years old