Please help! Derivatives

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?

What are the solutions of the equation x4 + 6x2 + 5 = 0? use u substitution to solve.

Solve -3 (r + 5) = -9 enter ur answer in the box x = __