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3. A demand function of a certain good is given by: Q=-20P + 0.04Y + 4T + 3Pr where Q and P denote the quantity and price of the good, Y is income, T is taste and, Pr is the price of a related good. a. (3 points). Calculate Q when P = 8, Y = 1000, T = 15 and Pr = 30. b. (3 points). Is the related good substitutable or complementary? Give a reason for your answer. c. (3 points). Find the value of P when Q = 235, Y = 8000, T = 30 and Pr = 25