In a job shop operation, four jobs may be performed on any of four machines. The number of hours required for each job on each machine is summarized in the table. Formulate a linear program to minimize the total time job-machine assignment.
Machine
Job A B C D
1 22 18 32 26
2 22 24 12 16
3 24 30 26 24
4 26 30 28 20