Bob consumes two goods, 3: and 3;. His utility function is given by \"(maul = my. Bob's income is $72 per day. The price of one unit of y is always $1 per unit. Yesterday, the price of one unit of good a: was $9. Today, the price of one unit of good a: is $4. Calculate the income, substitution and total effects for good a: of this price decrease of good 31:. In order to do so, compute yesterday's optimal bundle and today's optimal bundle for Bob, as well as the bundle that is optimal given the appropriate \"hypothetical\" budget line