3. (26 points) Joe has the following utility function: Q'X, Y) = 3J3? + J} , where X is his consumption of candy bars, with Px = $1, and Y is coffee, with Py = $2. (a) (8 points) Assume that his income is $100. How many candy bars and how much coffee will Joe consume? (b) (8 points) Suppose the price of coffee decreases from $2 to $1. What is the total effect of the price decrease on Joe's consumption of coffee? (0) (10 points) What is the substitution effect? What is the income effect