Let A = 30 B = 35 C = 40
Assume that all students do not go to class library at the same time. At a time either section A or section B or section c visit the library and read the books.
Find the maximum of A, B and C that is greatest integer of 30, 35 and 40.
largest value is 40.
If 40 books are kept in the library, every student in section A can get one book when section A goes to library. Same way every student in section B gets oone book when sectoion B visits library. Same for section C.