Final answer:
The budgeted change in inventory levels for the Willsey Merchandise Company in December is a $6,000 increase, calculated by taking the budgeted merchandise purchases of $18,000 and subtracting the cost of goods sold, which is $12,000 (30% of the $40,000 in sales).
Step-by-step explanation:
The Willsey Merchandise Company has budgeted $40,000 in sales for the month of December, with the cost of goods sold being 30% of sales. Therefore, the cost of goods sold equals $40,000 * 30% = $12,000. Since the company has budgeted to purchase $18,000 in merchandise during December, the budgeted change in inventory levels would be the budgeted merchandise purchases minus the cost of goods sold. This can be calculated as $18,000 (budgeted purchases) - $12,000 (cost of goods sold) = $6,000. Hence, the budgeted change in inventory levels is a $6,000 increase.