What is the value of the function, f(x)=x^2-5x when x=-5 ?

It says factor each expression completely 8y+48

What is the value of x when x + 7 = 21?

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?