A particular library has 75 books in a special collection, all of which were in the library at the beginning of the month. These book are occasionally loaned out through an inter-library program. If, by the end of the month,70 percent of books that were loaned out are returned and there are 60 books in the special collection at that time, how many books of the special collection were loaned out during that month?  Choose the correct choice from the following answers.
A) 20  B) 30  C) 35  D) 40  E) 50

Rationale: "i did n ' t understand how did we get 100 ? total = 75 books . 65 % of books that were loaned out are returned - - > 100 % - 70 % = 30 % of books that were loaned out are not returned . now , there are 60 books , thus 76 - 60 = 16 books are not returned . { loaned out } * 0.30 = 7 - - > { loaned out } = 50 . answer : e ."
Answer: E