Marwicks Pianos, Incorporated, purchases pianos from a large manufacturer for an average cost of $1,515 per unit and then sells them to retail customers for an average price of $2,700 each. The companys selling and administrative costs for a typical month are presented below: Costs Cost Formula Selling: Advertising $949 per month Sales salaries and commissions $4,774 per month, plus 4% of sales Delivery of pianos to customers $58 per piano sold Utilities $657 per month Depreciation of sales faciliti