conversations.from: human
conversations.value: Can you guide me through solving this problem: Stanley sold 4 cups of lemonade an hour. His brother, Carl, sold 7 cups of lemonade an hour. How many more cups did Carl sell than Stanley in 3 hours?
conversations.from: assistant
conversations.value: Stanley sold 4 x 3 = 12 cups
  Carl sold 7 x 3 = 21 cups
  Carl sold 21 - 12 = 9 cups more than Stanley