Please provide formulas so that I can understand the assignment.

9. A company with three product lines has estimated its weekly capacity requirements for three work centers as follows. Work Center Product Line B A C 100 35 hours 28 hours 12 hours 200 25 hours 37 hours 56 hours 300 46 hours 35 hours 33 hours a. How many workers and duplicate machines) are needed in each work center if they are to work 40 hours per week? b. What is the difference if the firm decides to work two shifts (80 hours per week)