Hello, Cheerbunny.
Given: We already know that there are 36 books total. This means that if every shelf has the same amount of books, each shelf will have 4.
If 36 is divided into 6 equal groups, then this makes [tex]\frac{36(books)}{6(shelves}[/tex]. 36/6 is 6, so this means that each shelf will have 6 books.
An array of this would be six units wide and six units long.
I hope this was helpful.
