There are 320 popular science books in the school, accounting for 2/5 of all books, and story books account for 4/3. How many story books are there in the library?
There are 320 popular science books in the school, accounting for 2/5 of all books, so all books are:
320/5 2 = 320 * 5 = 800 copies.
Popular science books are equivalent to four-thirds of story books, so story books are:
320/3 = 320 * 4=240.
A: There are 240 copies.