19. The demand functions for two products are given below. p1, p2, q1,and C12 are the prices (in dollars) and quanties for products 1 and 2. QI = 200 _3p1+ :02 92 =150 +p1-2p2 a. Are these two products complementary goods or substitute goods? b. What is the quantity demanded for each when the price for product 1 is $20 per item and the price for product 2 is $30 per item? 0. Write a function R(p1,p2)that expresses the total revenue from these two products. d. Find the price and quantity for each product that maximizes the total revenue