Consider the following linear programming problem Min A+ 2B s.t. A + 4B< or equal to 21 2A + B > or equal to 7 3A + 1.5B < or equal to 21 -2A + 6B > or equal to 0 A, B > or equal to 0 a. Find the optimal soulution using the graphical soulution procedure and the value of the objective function b.determine the amount of slack or surplus for each constraint c. suppose the objective function is changed to max 5A+2B. Find the optimal solution and the value of the objective function. .