a) Partially solve the IP model graphically (for l-1 and 1-2, two sketches only) by using the Branch- and-Bound Method (Use a graph paper or other graphing sheet but be sure to implement a reasonable scalc). Show the feasible region, and plot the objective function through the optimal point as a dashed line (---) for each subproblem solution. Indicate the optimal values of the variables and objective function for each subproblem solution and indicate all additional constraints, as shown below. When you need for branch, branch on xl, first if there are two choices. Indicate all additional constraints from t1 to create the subproblems and all additional constraints from 2 to create the subproblems. Maximize Z = 2xy + 3x2 Subject to: 4x + 2x2 2x + 5x, X, X VIVA 20 (CI) 30 (C2) 0, xl, xa integer Tori 1. show the results. (x1, x2) - Z- All constraints added to t 1 to create subproblems: Constraint added to ti to create t=2: Fort2. show the results: (X1, X2) Z All constraints added to t2 to create subproblems b) Write the IP model needed to solve the problem in LINDO with labeling its constraints Use INT or GIN as an appropriate in LINDO