There are 312 books in total.
Let 'x' represent the number of FICTION books.
There are 11x NONFICTION books and 1x FICTION books.
1x+11x=312
12x=312
Now divide 12x by 12 and 312 by 12 (whatever you do to one side of the equals sign you have to do to the other)
Once you do that you will get 1x=26
This means you have 26 fiction books. Now, you have 11 times as many nonfiction books so 26x11=286
This means you have 286 nonfiction books
To check your answer add 286 and 26 to make sure it adds to 312.
