Library collection 1278 volumes, of which science and technology books are half of literature and art books, and literature and art books are one-third of comics books. How many copies of each of these three books have been sold? Solution: run a comic book and sell X copies.

1/3x+ 1/3 * 1/2x+x = 1278

3/2x= 1278

x=852

Literature books: 1/3*852=284.

Science and technology books: 1/2*284= 142.