Robert views X and Y as perfect substitutes in his consumption, and MRS = 1 for all combinations of the two goods in his indifference map. Suppose the price of X is $6 per pound, the price of Y is $4 per pound, and Robert's budget is $60 per week. What is Robert's initial utility maximizing choice between these two goods? Why? Suppose now that the price of Y increases to $8 per pound. What is his new utility maximizing choice? What is the size of the substitution and income effects for Y?
*Question must be supported with relevant diagram and explanations.