Given the demand function Q = 400 - 3P + 2PA + 0.5Y, where P = 20, P A = 25, and Y = 2500, nd a) the price elasticity of demand, b) the cross-price elasticity of demand, and c) the income elasticity of demand. Is the alternative good substitutable or complementary? W a) IEPI = [:l (Round to three decimal places as needed.) b) E = D (Round to three decimal places as needed.) P A c) EY = D (Round to three decimal places as needed.) is the alternative good substitutable or complementary? O substitutable O complementary