There are 9 different books and 10 different movies in the ' crazy silly school ' series. If you read 33 of the movies and watched 21 of the books How many more movies than books have you read?
There are 9 different books and 10 different movies in the 'crazy silly school' series. 

If you read 33 of the movies and watched 21 of the books, you would have read 12 more movies than books.