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?
Half the number of pages of Selena is 400/2 = <<400/2=200>>200.
Therefore, Harry's book has 200 - 20 = <<200-20=180>>180 pages.
#### 180