3. Andy Dwyer's band has a new album out. The demand for their music is characterized by the following demand function: Sn where p denotes the price of their album. Each CD costs $3 to make. a. Please derive the marginal revenue curve? [3 points] b. How much should Andy Dwyer charge for the CD and how many CDs would he sell? [5 points] c. What is the social optimum number of CDs? [3 points] d. Please draw a graph to indicate what you found in Parts a to c. [4 points]