The ratio of the number of science and technology books to story books in the school library is 5: 8, and the number of science and technology books is less than story books 120. How many science books and story books are there? Assuming that science and technology books are divided into five parts and storybooks can be divided into eight parts, there are three more storybooks than science and technology books, and there are more storybooks in the title than science and technology books 120, that is, one is 120÷3=40 (this).

Therefore, there are: 40×5=200 (copies)

Story books are: 40×8=320 (book)