The president of Hill​ Enterprises, Terri​ Hill, projects the​ firm's aggregate demand requirements over the next 8 months as​ follows: January May February June March July April August Her operations manager is considering a new​ plan, which begins in January with units of inventory on hand. Stockout cost of lost sales is ​$ per unit. Inventory holding cost is ​$ per unit per month. Ignore any​ idle-time costs. The plan is called plan A. Plan​ A: Vary the workforce level to execute a strategy that produces the quantity demanded in the prior month. The December demand and rate of production are both units per month. The cost of hiring additional workers is ​$ per unit. The cost of laying off workers is ​$ per unit. Evaluate this plan. ​(Enter all responses as whole numbers​.) ​Note: Both hiring and layoff costs are incurred in the month of the change. For​ example, going from in January to in February incurs a cost of layoff for units in February.