On December 31, 2017, Ling Co. estimated that 3% of its net sales of $408,000 will become uncollectible. The company recorded this amount as an addition to Allowance for Doubtful Accounts. On May 11, 2018, Ling Co. determined that the Jeff Shoemaker account was uncollectible and wrote off $2, 040. On June 12, 2018, Shoemaker paid the amount previously written off. Prepare the journal entries on December 31, 2017, May 11, 2018, and June 12, 2018