aggregate planning. Can you explain each step? I do not understand how to get the answers for this aggregate planning. answers are provided. what are the formulas used?

A manager has prepared a forecast of expected aggregate demand for the next six months. Develop an aggregate plan to meet this demand given this additional information: A level production rate of 200 units per month will be used. Backorders are allowed, and they are charged at the rate of $3 per unit per month. Inventory carrying costs are $1 per unit per month. Level plan: 1. Regular time production Determine the cost of this plan if regular time cost is $4 per unit and beginning inventory is 10 units. 2. inventory 3. Backorders