6. (8 points) Sandford has the utility mction u(x, y) = Zlnx + 4171]) dened over positive values of x and 3}. His preferences are strongly monotonic and strongly convex. You do not need to verify this in your answer. (a) (2 points) Find his demand functions for x and y as functions of prices and income. You need to derive these demand functions using some method, not simply state them. (b) (3 points) Derive the cost minimizing demand mctions as a function of utility u > 0 and prices. (c) (3 points) Suppose that the prices are px = 1, p3, = 1 and income M0 = 100. Calculate the substitution and income effect if the price of 37 increases from 1 to 10