Answer question 21) - 24) based on the problem description below. Luckman Shipping Co. is deciding on which items to load on a van of 2000 pounds capacity. The items awaiting shipment have values and weights specified by the table below. Item Value (in $1000) Weight (pound) 1 500 1000 2 625 1200 3 300 400 4 350 600 5 450 850 UTH The goal of the firm is to maximize the total value shipped. Also, the following requirements are stipulated by the logistics optimization department: (i) Item 1 can be shipped only if item 4 is shipped. (ii) Item 2 and item 3 cannot be shipped together. To solve this problem, the manager decides to set up a mixed integer program (MIP) and he defines the following decision variables: X; = 1 if itemj is chosen, otherwise X; = 0; j = 1, ..-5. = 22) (3 points) To express the requirement (i), the constraint is