answer: #Person1# assists #Person2# in buying a toy car for #Person2#'s son.
documents: #Person1#: What can I do for you, madam?
  #Person2#: I'd like to buy a toy car for my son.
  #Person1#: How about this one?
  #Person2#: It looks nice. How much is it?
  #Person1#: They're three hundred dollars.
  #Person2#: Oh, I'm afraid it's too expensive. Can you show me something cheaper?
  #Person1#: OK, This one is one hundred and twenty. It's the cheapest here.
  #Person2#: OK, I'll take it. Here's the money.
  #Person1#: Thank you very much.