Final answer:
To find how many books remain in Shane's collection, subtract the number of books he donated, sold to a rare book dealer, and sold on eBay from the total number of books in his collection.
Step-by-step explanation:
To find how many books remain in Shane's collection, we need to subtract the number of books he donated, sold to a rare book dealer, and sold on eBay from the total number of books in his collection.
Shane donates 1/5 of his books, which is 40 x 1/5 = 8 books.
He sells 1/4 of his books, which is 40 x 1/4 = 10 books.
He also sells 4 additional books on eBay.
To calculate the number of books remaining, we subtract the total number of donated, sold, and eBay books from the initial total. 40 - 8 - 10 - 4 = 18 books.