An income statement for Sam's Bookstore for the first quarter of the year is presented below: Sam's Books tore Income Statement For Quarter Ended March 31 Sales $880,000 Cost of goods sold 540,000 Gross margin Selling and administrative expenses 340,000 Selling Administration $115,000 134,000 249,000 Net operating income $ 91,000 On average, a book sells for $55. 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 number of books sold is The cost formula for selling and administrative expenses with "X" equal Multiple Choice Y $135,000+$6.00x Y $135,000+$8.75X Y $109.000 + $8.75X Y $109.000+ $11.50x