In ABC Bookstore, 40% of the books are non-fiction books. 70% of the remainder are fiction books and the rest are Assesment books. There are 30 more fiction books than non-fiction books. After some non-fiction books are sold, 25% of the remaining books are non-fiction books. How many books are left altogether?

 Aug 1, 2021

Hi, to start with, let's assign a variable to make things easier.


-set x as the total number of books.


-Given, 4/10x are non-ficiton

-Given, 6/10(the remaining) times 7/10 = 42/100x are fiction

-And Given, the rest(100/100- 82/100)x, which is 18/100x, is assesment books.

The question asks us to find how many books are left, and the information 30 more fiction than non-fiction comes handy here.


(42/100-40/100)x is exactly thirty books! than means 1/50 is 30 books, so there are 30*50=1500 books in total.


Finally, After some non-ficiton books are sold, only 25% of the remaining books are non-fiction books.We can re-write that as-


40% of total- some amount(600-y)/total minus same some amount(1500-y) = 25/100. We need to find y.


Here I'll just skip the process of solving this equation and say y is 300, which leaves us with 300/1200 which is 25 percent. So, now with 1500-300 we get our final answer here which is there are 1200 books left altogether now. And hopefully this explanation proves to be helpful.

 Aug 1, 2021

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