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 2:17 Sales $ 840,000 Cost of goods sold Gross margin 525,000 315,000 Selling and administrative expenses Selling $ 112,000 Administrative 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 cost formula for selling and administrative expenses with "X" equal to the number of books sold is: