Armstrong Inc. is a calendar-year corporation. Its financial statements for the years ended 12/31/20 and 12/31/21 contained the following errors:

	2020	2021
Ending inventory	$15,000 overstatement	$24,000 understatement
Depreciation expense	$6,000 understatement	$12,000 overstatement

Assume that no correcting entries were made at 12/31/20 or 12/31/21. Ignoring income taxes, by how much will retained earnings at 12/31/21 be overstated or understated?

Group of answer choices

$30,000 understatement

$24,000 overstatement

$21,000 overstatement

$9,000 understatement