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			$	910,000
Cost of goods sold				560,000
Gross margin				350,000
Selling and administrative expenses
Selling	$	119,000
Administration		142,000		261,000
Net operating income			$	89,000

On average, a book sells for $65. Variable selling expenses are $4 per book with the remaining selling expenses being fixed. The variable administrative expenses are 3% 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: