Formulate the appropriate linear program

In a job shop operation, four jobs may be performed on any of four machines.
The hours required for each job on each machine are presented in a following table.
The plant supervior would like to assign jobs so that total time is minimized.
Find the best solution. Formulate the appropriate linear program and solve uisng Excel Solver. Show your work. (20 points)

COSTS Machine 1 Machine 2 Machine 3 Machine 4
A12 10 14 16 13
A15 12 13 15 12
B2 9 12 12 11
B9 14 16 18 16

Solution: