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4. Don's Used Cars reported Net Income of $13,000 for 2020 and had a beginning Retained Earnings balance of $20,000 credit. The company also found the following errors in its prior year income statements. In 2018, the company did not record $12,000 in administrative expenses. In 2019, the company failed to record a gain on the disposal of equipment for $18,000. Assuming a 30% tax rate for every year, what was the ending Retained Earnings balance on December 31, 2020 ? a. $39,000 b. $54,000 c. $28,800 d. $37,200