Contribution margin, break$-$even sales, cost$-$volume$-$profit chart, margin of safety, and operating leverageBelmain Co$.$ expects to maintain the same inventories at the end of $20$Y$7$ as at the beginning of the year. The total of all production costs for the year is therefore assumed to be equal to the cost of goods sold. With this in mind, the various department heads were asked to submit estimates of the costs for their departments during the year. A summary report of these estimates is as follows:Line Item DescriptionEstimatedFixed CostEstimated Variable Cost$($per unit sold$)$Production costs:Direct materials$$15$Direct labor$10$Factory overhead$$177,4008$Selling expenses: Sales salaries and commissions$36,9003$