Pine Aviation begins business in 2013. During its first year its credit sales are $350,000. Uncollectibles are estimated at 4% of credit sales. The next year, $10,000 of bad debts are written off and an additional $400,000 of credit sales are booked. How much is bad debt expense for 2013? What is the balance of the allowance for bad debts at the end of 2013?