4. A consumer has a utility function u(X1, X2) = 1/{(1/X1) + (4/X2)}, with prices of the two goods PX1 and PX2 respectively. If his total income is given by m: (10 marks) (a) Find this consumer's Marshallian demand function for each good. (4) (b) Find this consumer's indirect utility function. (3) (c) Find this consumer's expenditure function. (3)