Suppose the market demand for wheat is as follows: Qd = 45 - 2P + 0.3Y + 1Pb where Y refers to income and Pb refers to the price of barley. a. (1) Assuming that wheat and barley both sell for $1 per unit and income is $20, calculate the price elasticity, cross-price elasticity, and income elasticity for wheat. b. (1) If income drops by 10%, calculate the percentage change in demand for wheat.