calculate avoidable interest and what is the total cost of the projecy

On March 1, 2020, AUS Company purchased land for an office site. AUS began construction on the office building on March 1. The following expenditures were incurred for construction: Date Expenditures March 1, 2020 $ 1,800,000 April 1, 2020 2,520,000 July 1, 2020 4,500,000 December 1, 2020 4,800,000 The office was completed and ready for occupancy on December 31. To help pay for construction 3,600,000 was borrowed on March 1, 2020 on a 9%, 3-year note payable. Other than the construction note, the only debt outstanding during 2020 was a $3,500,000, 12%, 6-year note payable dated January 1, 2020