An income statement for Sam's Bookstore for the first quarter of the year is presented below: Sam's Bookstore Income Statement For Quarter Ended March 31 Sales $840,000 525,000 Cost of goods sold Gross margin Selling and administrative expenses 315,000 Selling $112,000 Administration 128,000 240,000 Net operating income $ 75,000 On average, a book sells for $60. Variable selling expenses are $6 per book with the remaining selling expenses being fixed. The variable administrative expenses are 5% of sales with the remainder being fixed. The net operating income using the contribution approach for the first quarter is