<human>:  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?
<bot>: How many pages are in Selena's book? ** Half the number of pages of Selena is 400/2 = <<400/2=200>>200.
How many pages are in Harry's book? ** Therefore, Harry's book has 200 - 20 = <<200-20=180>>180 pages.
#### 180