This is about consumer theory in microeconomics. Please show all your workings and explanations and answers. Please answer all parts

Question Three (8 Marks) Lulu has a utility function of U(X, Y) = (X0'4Y0-6) for goods X and Y. Assume that she is a utility maximising consumer who spends all of her weekly budget of $1 8 on goods X and/0r Y. T he price of good X is $1.40, while the price of good Y is $1.60. (a) Calculate Lulu's best affordable bundle. (b) Prove that the bundle you calculated in (a) above is affordable. (c) Explain What happens to Lulu's marginal rate of substitution as you move down her indifference curve? As part of your answer, explain What marginal rate of substitution means