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 Cost of goods sold Gross margin Selling and administrative expenses Selling Administration Net operating income $900, eee 555,000 345,000 $118,000 140,eee 258, eee $ 87,000 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 contribution margin for Sam's Bookstore for the first quarter is: O $255,000 O O $765,000 O $210,000 $690.000