Academic Dishonesty Investigations Ltd. operates a plagiarism detection service for universities and colleges. Required: 1. Prepare journal entries for each transaction below. (If no entry is required for a transaction/event, select "No journal entry required" in the first account field.)

1. On March 31, ten customers were billed for detection services totalling $40,000.
2. On October 31, a customer balance of $2,400 from a prior year was determined to be uncollectible and was written off.
3. On December 15, a customer paid an old balance of $1,650, which had been written off in a prior year.
4. On December 31, $1,050 of bad debts were estimated and recorded for the year.

2. Complete the following table, indicating the amount. Ignore income taxes. (Enter any decreases with a minus sign.)

Net Receivables	Net Sales	Income from Operations
a. b c d