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		$ 950,000
Cost of goods sold		650,000
Gross margin		300,000
Selling and administrative expenses
Selling	$ 104,000
Administrative	112,000	216,000
Net operating income		$ 84,000

On average, a book sells for $50. 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: