I need help yall lol​

Ined this is due tomorrow and i dont know the answer can you find all the exponents

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?

Collin did the work to see if 10 is a solution to the equation r/4=2.4