QI: (5) a. When there are more than two decision variables, then solving a linear programming problem by graphical method is feasible or not, Why? (5) b. Maximize Z = X + 2Y subject to the constraints: X23, X+Y25, X + 2Y 26, 720 c. Philips's incorporation manufactures 02 types of tube lights (Type A and Type B). The Type A requires twice the labor time as Type B. If the company dedicates all the labor to manufacture only Type 2 tube lights, only 400 quantities can be manufacture per day. The daily market demand for the Type A and Type B are 150 and 200 tube lights. The profit on Type A and Type B is 8 USD and 5 USD respectively. Determine the optimum number of tube lights that will maximize profit. (15)