4. 'Wick Industries makes and sells two products, X1 and X2. The unit contribution margin of X1 is $6, and the unit contribution margin of X2 is $24. The production process for both products requires processing time in Departments A and B. Each unit of X1 requires 12 labor hours in Department A and 4 labor hours in Department B. Each unit of X2 requires 6 labor hours in Department A and 8 labor hours inDepartment B. There are 360 labor hours available in Department A and 240 hours available in Department B. a. Using Solver, What product mix will maximize total contribution? I b. Using Solver, solve the dual linear program for the linear program you solved in part a. c. For the dual linear program you solved in part b, are either of the dual variables (V A or VB) equal to zero? If so, Why do you think this is the case