There are 50 different books and 15 different movies in the ' crazy silly school ' series. If you read 15 of the movies and watched 31 of the books How many more books than movies have you read?
There are 50 different books and 15 different movies in the 'crazy silly school' series. 

If you read 15 of the movies, that means you have 35 movies left to watch. 

And if you watched 31 of the books, that means you have 19 books left to read. 

So, you would have to read 16 more books than movies.