What is the LCD of 1/9,1/15,1/5

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

Interest begins accruing the date of the transaction except for auto loans mortgages credit card cash advances credit card purchases

Barney & noblet customers can choose to purchase a membership for $25 per year members receive 10% off all store purchases 1. how much would a member pay per year if he bought $50 worth of items each year? 2. write a slope-intercept equation that expresses how much a member pays per year using x to represent his purchases per year 3. how much would a member have to spend per year to pay off his membership fee?