50 people sponsor paula and she raises a total of £180 for charity. what is the mean average amount sponsored

If x = 12 and y = 3, what is the value of x - y 2? 81 6 3 18

Ineed to know the answer to this algebra question.

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?