Abookstore has a sale on travel books. customers can purchase one book for the full price of $18.50 and then as many other travel books as they want for half of that price. if y represents the total cost and x represents the total number of books purchased, which function rule describes this situation?

If it is desired to buy x books, the first one would cost $18.50. All the books brought after that would only cost $9.25. The number of books that would cost have is x - 1. The expression that would relate the total cost to the number of books purchased is,
                                   18.5 + (x - 1)(9.25) = y