A person is earning revenue by selling quilts on Etsy. The amount of revenue they earn R(n,p) is a function of the number of quilts they sell, n, and the price they charge for each quilt, p. However, the number of quilts they sell is itself a function of the price, n=n(p) [since a high price usually means fewer sales]. a) Use a tree diagram to show the relationship between the variables R,n, and p. b) Write down an expression for dp/dR that comes from applying the chain rule.