answer: #Person1# buys a dozen of roses which are on sale for his wife's birthday.
documents: #Person1#: My wife's birthday is today. I need some flowers. 
  #Person2#: We have lots of fresh red roses. 
  #Person1#: How much do the roses cost? 
  #Person2#: $20 a dozen. 
  #Person1#: That sounds good. Last year I paid $30. 
  #Person2#: Yes, you came here on the right day. They're on sale today. 
  #Person1#: Give me a dozen. 
  #Person2#: Very good. Would you like anything else? 
  #Person1#: No, I'll just give her the roses and a card. 
  #Person2#: She should be very pleased with these roses.