Restate the following income statement for a retailer in contribution format. Sales revenue ($100 per unit) $ 72,000 Less cost of goods sold ($60 per unit) 43,200 Gross margin 28,800 Less operating costs: Commissions expense ($7 per unit) $ 5,040 Salaries expense 7,800 Advertising expense 5,900 Shipping expense ($1 per unit) 720 19,460 Operating income $ 9,340 $ $ Sales Revenue Shipping Expenses Salaries Expenses Cost of Goods Sold Variable Expenses Total Fixed Expenses Fixed Expenses Advertising Expenses Total Variable Expenses Contribution Margin Commissions Expenses Operating Income $ $