please include excel formulas

2) A manager has prepared a forecast of expected aggregate demand. Develop an aggregate plan that assumes: A level production rate, back orders are allowed and are charged at the rate of $12 per unit per month, inventory holding costs are $3 per unit per month in average inventory, regular time cost is $9 per unit and beginning inventory is zero. Show the aggregate plan and determine the cost of this plan. (15 pts) Month Forecast 280 280 270 340 330 300