Using the above data how would i vary the work force level

Question

1. Each nurse works 40 hours per week of regular time.
2. Nurses are paid $25.00 per hour of regular time (this includes fringe benefits)
3. Nurses are paid $35.00 per hour of overtime worked per period (this includes fringe benefits)
4. Maximum number of overtimes hours able to be worked per nurse per period is 43.45 hours or 25% of the regular time worked.
5. Agency nurses (subcontracted labor) costs $42.00 per hour. Subcontracted nurses are paid for the entire period when they are used.
6. It is estimated to cost $4,100 to hire one permanent nurse.
7. The firing cost is estimated to be equal to two-weeks salary for a nurse.
8. There are twelve equal months per year. (Make sure that you calculate how many regular time hours are worked each period when the year is divided into twelve equal periods).

Using the above data how would I vary the work force level to meet exactly the demand requirements by hiring or firing nurses each month?