Let the demand function for books be QB = 30-3PB, where QB is the number of books purchased and PB is the price of books. a. Derive and plot the demand curve based on this function (with PB on the vertical axis and QB on the horizontal axis). (5 points) b. Is the demand for books more elastic between PB = 2 and PB-3, or between PB=8 and PB = 9? Explain. (5 points) c. Suppose that this person experiences an increase in income. Assuming books are a normal good, illustrate and explain the impact of this income increase on the demand curve you plotted in (a). (5 points) d. Suppose that on-demand movies are a substitute for books, and that the price of on-demand movies declines. Illustrate and explain the impact of this change on the demand curve you drew in part (a). (5 points)