Find the optimal solution for the following problem (Round your answers to 3 decimal places.) Maximize subject to 7x + 9 + 6 12x + y + 157 $ 72 9x + 3y + 5z 5 144 and a. What is the optimal value of b. What is the optimal value of y? c. What is the optimal value of ? d. What is the maximum value of the objective function? Maximum value