4. Demand for good X is given by the following equation: Q = 40 - 2P, where Q is quantity demanded and P is price. a) Draw this demand curve below. (5 points) b) Find the price elasticity of demand when P-10 and interpret it. What does this point imply about total revenue? (10 points) c) Find the price elasticities of demand between P=18 and P=19 and between P-1 and P=2. Evaluate these elasticity values in terms of change in total revenue. Use your own words. (16 points)