Let the common ratio for English and Hindi fiction books be 2x and 3x respectively.
Given, English fiction books = 420 = 2x
Therefore, x = 210
So, Hindi fiction books = 3x =\( 3 \times 210\) = 630
Total fiction books = English fiction + Hindi fiction = 420 + 630 = 1050 books
Total number of books in the library.
Let the common ratio for fiction and non-fiction books be 7y and 5y respectively.
We know, total fiction books = 1050 = 7y
Therefore, y = 150
So, total non-fiction books = 5y = \(5 \times 150 = 750\) books