Please explain how the problems are done so I understand.

1. J-Pac Co. uses the allowance Method to account for uncollectible Accounts Receivable. If they determine that customer Matt Evans' balance of $900 is uncollectible, the correct entry to write it off would be:

2. The Gallante Smoke Shop had written off a $550 receivable owed by P. Lang. Several months later, Lang remitted the $550. Gallante Smoke Shop should record the following:

3. Calculate the amount of interest that would be earned on a $12,000 9% 4 month note receivable.