21. LO.5 David is the sole proprietor of a real estate construction business. He uses the completed contract method on a particular contract that requires 16 months to complete. The contract is for $500,000, with estimated costs of $300,000. At the end of 2020, $180,000 of costs had been incurred. The contract is completed in 2021, with the total cost being $295,000. Determine the amount of adjustments for AMT purposes for 2020 and 2021.