please show workings and formulas used.

Efalan Corporation produces a single product. The cost of producing and selling a single unit of this product at the company's normal activity level of 80,000 units per month is as follows: The normal selling price of the product is $67.80 per unit. An order has been received from an overseas customer for 3,000 units to be delivered this month at a special discounted price. This order would not change the total amount of the company's fixed costs. The variable selling and administrative expense would be $1.90 less per unit on this order than on normal sales. Direct labor is a variable cost in this company. Suppose there is ample idle capacity to produce the units required by the overseas customer and the special discounted price on the special order is $60.60 per unit. The monthly financial advantage (disadvantage) for the company as a result of accepting this special order should be: ($4,200)$84,300($15,900)$27,300