Suppose we are developing a model where rij is a binary variable describing whether job i is assigned to machine j, i {1,...,m} and j {1,...,n}. Write linear constraint (s) to ensure that a. Each job can be assigned to at most 2 machines. b. We cannot assign more than 3 jobs to machine 5. c. If job 1 is assigned to machine 2, then job 3 should be assigned to machine 4. d. The number of jobs assigned to machine 5 is not less than the total number of jobs assigned to machine 7 and machine 9. e. If jobs 3, 4 and 5 are assigned to machine 2, then job 5 cannot be assigned to machine 3.