Alderwood Company has provided the following information prior to any year$-$end bad debt adjustment:

Cash sales, $$450,000$

Credit sales, $$1,350,000$

Selling and administrative expenses, $$330,000$

Sales returns and allowances, $$90,000$

Gross profit, $$1,470,000$

Accounts receivable, $$330,000$

Sales discounts, $$42,000$

Allowance for doubtful accounts credit balance, $$3,600$

Alderwood prepares an aging of accounts receivable and the result shows that $5\%$ of accounts receivable is estimated to be uncollectible. How much is bad debt expense?