What is the difference between a formal and informal proof? a formal proof uses a table or a list of steps, whereas an informal proof uses paragraphs. a formal proof uses equations, whereas an informal proof only uses text. a formal proof is much shorter, whereas an informal proof is longer. a formal proof provides the reasons for steps, whereas an informal proof does not.

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?