We have to write a recursive formula that represents the number of books Ashley has at any time. At start Ashley has 100 books. If y is the number of books she has at any time, n is the number of books she wants to give away each week and x is the number of the weeks: y = 100 - n x . For example: n = 5. After 10 weeks: x = 10 and y = 100 - 5 * 10 = 100 - 50 = 50 books. Answer: y = 100 - n x.