Whiterun Ltd owned a boat that has an economic useful life of 6 years as at 1 July 2020. On 1 July 2020 the company leased the boat to Riverwood Ltd. In the lease agreement, Riverwood Ltd agreed to guarantee $4 000 residual value. The lease payment is $20,000 for three years. Lease payments are to be made annually and in advance. The interest rate implicit in the lease is the same for both companies at 5%. What is the amount of Riverwood Ltd's lease liability on the commencement day of the lease?