the public library where i work originally had one hardcover and two paperback copies of every book that sir arthur conan doyle ever wrote. the records for the month of march show that member $7427$ checked out all of the hardcover conan doyle books and never brought them back. the following month, a group of other members checked out every conan doyle book left in the library building. each of those members took the same number of books, and that number equaled one ninth of our original collection. two of those members brought their books back on time. it's my job to call the other people who checked out conan doyle books, including member $7427$, and demand the return of their overdue items. how many angry phone calls do i have to make?