Please explain how to do this Im rly confused:

Calistoga Produce estimates bad debt expense at 0.20% of credit sales. The company reported accounts receivable and allowance for uncollectible accounts of $478,000 and $1570 respectively, at December 31, 2017. During 2018, Calistoga's credit sales and collections were $330,000 and $305,000, respectively, and $1860 in accounts receivable were written off. Calistoga's 2018 bad debt expense is: