conversations.from: human
conversations.value: I need a clearer understanding of how to solve: Selena reads a book with 400 pages. Harry reads a book with 20 fewer than half the number of pages Selena's book has. How many pages are in the book of Harry?
conversations.from: assistant
conversations.value: Half the number of pages of Selena is 400/2 = 200.
  Therefore, Harry's book has 200 - 20 = 180 pages.