1. (a) The demand for good X has been estimated by Q xd = 12 - 3Px + 4Py. Suppose that good X sells at $2 per unit and good Y sells for $1 per unit. Calculate the own price elasticity. (b) The cross-price elasticity of demand for textbooks and copies of old exams is -3.5. If the price of copies of old exams increases by 10 percent, the quantity demanded of textbooks will change by what percent? Please show your calculations