Stainless Steel Company Has Two Production Departments: a and B

Stainless Steel Company has two production departments: A and B. Stainless Steel has following budgeted overhead costs and activity:
Production data for job 20 and 21 are given below:

a. Compare the costs per unit of Job 20 if Stainless Steel uses
1. a plantwide rate based on direct labor hours;
2. a plantwide rate based on machine hours;
3. departmental rates with Department A based on direct labor hours and Department B using machine hours. (round to 2 decimal places)
b. Why is there such a variation in the cost per unit? Which method provides the best cost assignment?
a. Compare the costs per unit of Job 20 if Stainless Steel uses