conversations.from: human
conversations.value: I need help with this problem:
  At a certain bookstore, the best-selling book, "TOP," costs $8. The least-selling book, "ABC," costs $23. Thirteen "TOP" books and four "ABC" books were sold last week. What is the difference in the bookstore's earnings on these two books last week?
conversations.from: assistant
conversations.value: On "TOP" books the bookstore made 13 * 8 = $104.
  The "ABC" books, on the other hand, were sold for a total of 4 * 23 = $92.
  The difference between earnings from these two books is 104 - 92 = $12.