The library purchased 540 books of three categories, among which science and technology books accounted for 13 of the total, and literature and art books accounted for 45% of children's books. How man
The library purchased 540 books of three categories, among which science and technology books accounted for 13 of the total, and literature and art books accounted for 45% of children's books. How many children's books have you bought?
4+5=9,
(540-540× 13)×59,
=(540- 180)×59,
=360×59,
=200 (Ben),
Answer: I bought 200 children's books.