There are 100 books in the library, and those who borrow the books need to sign on the books. Among these 100 books, there are 33, 44, and 55 books signed by A, B, and C respectively. Among them, both A and There are 29 books signed by B, 25 books signed by both A and C, and 36 books signed by both B and C. Ask how many books in this batch of books are at least not borrowed by anyone A, B, or C?

Analysis: A*** signed 33 books, so the number of books signed by A and B is 29, and there are 4 books left. The problem is that there are 25 books signed by C at the same time, which means that there are at least 25-4 = 21 books signed by all three people. If you can confirm the book signed by the three people, it will be easier to do later.

33-29=4 (original)

25-4=21 (original) (This is signed by three people ***)

A and B People sign 29-21=8 (book)

A and C sign 25-21=4 (book)

B and C sign 36-21=15 (book)

C single signature 55-21-4-15=15 copies

100-(21+8+4+15+15)=37 (books)

Answer: There are at least 37 copies It has not been borrowed by any of the three people