21:55 0 5G 71 (III) The firm's production function is f (x) = [3x1 + 4x2]. (a) What are the returns to scale for this production function? Draw some isoquants for it. (b) Find, whenever it exists, the solution to the profit maximization problem for output price p and input prices (w1, W2). (c) Find the conditional factor demand, the cost function and the average cost function for this production function and illustrate all of them. (IV) The production function is f(21, X2) = In(x1 + 1) + In(x2 + 1). (a) Illustrate some isoquants for this production function. (b) Find the cost function for this production function and illustrate it. (V) The production function is f(X1, 2) = 0 for X2