Boersma Sales, Inc.is a merchandising company. Its records sho December 31, 2016: Sales were 7,000 units at a selling price of $60 per unit. Cost of goods sold, which is a variable cost, was $28 per unit. Variable selling expenses were $4 per unit. Variable administrative expenses were $2 per unit. Total fixed selling expenses were S15,000. Total fixed administrative expenses were $20,000. REQUIRED: Calculate total sales revenue Calculate total gross margin [2] [3] [4] Calculate total contribution margi Calculate operating income