The manager of a bookstore ordered 480 copies of a book. The manager paid a total of $7,440 for the books. The books arrived at the store in 5 cartons. Each carton contained the same number of books. A worker unpacked books at a rate of 48 books every 2 minutes. The manager unpacked books at a rate of 54 books every 3 minutes. How many minutes did the worker need to unpack 240 books?