What is the value of this expression?

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

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?

Two angles are complementary. the larger angle is 36 more than the smaller angle. what is the measure of the larger angle?