how to calculate the interest expenses?

Current agreement Lease period: Lease payment amount: Lease payment timing: Renewal agreement Lease period: Lease payment amount: Lcase payment timing: 15 mths with effect from 01.04.19 to 30.06.20 2,229.00 Beginning of the month 24 mths with effect from 01.07.20 to 30.06.22 2.080.40 Beginning of the month C SS 81,870.13 ROU Assets (FA) (a) Initial measurement of the lease liability (b) Initial direct cost (c) Prepaid lease payment (d) Lease incentives received Estimated decommissioning cost (eg: dismantling/removal/ restoration costs) Right-of-use Asset 395.06 82.265.19 2,229.00 Pay at beginning of period 15 Remaining 15 mths from 01.04.2019 2.25% Management determined 33,000.52 Lease viabilities schedule- Operating lenses (current agreement) Rental Terms Discount rate Present Value Lease liabilities schedule-Operating leases (renewal agreement) Rental Terms Discount rate Present Value Decommissioning cost Estimated decommissioning cost Terms Present Value 2,080.40 Pay at beginning of period 24 Remaining 24 mths from 01.07.2020 2.25% Management determined 48,869.61 425.00 Management determined 39 Total remaining period (15+24mths) 395.06 Date Mths FY2020 1 2 3 4 5 6 7 8 9 10 11 12 1/4/2019 1/5/2019 1/6/2019 1/7/2019 1/8/2019 1/9/2019 1/10/2019 1/11/2019 1/12/2019 1/1/2020 1/2/2020 1/3/2020 Principal b/ SS 33,000.52 30,829.22 28.653.84 26,474.39 24,290.85 22.103.21 19,911.48 17,715.63 15,515.67 13,311.58 11,103.36 8.891.00 Lease payment SS (2,229.00) (2,229.00) (2,229.00) (2,229.00) (2,229.00) (2.229.00) (2,229.00) (2,229.00) (2.229.00) (2,229.00) (2,229.00) (2,229.00) (26,748.00 Interest expense S$ 57.70 53.63 49.55 45.46 41.37 37.26 33.15 29.04 24.91 20.78 16.64 12.49 421.97 Principal cif S$ 30,829,22 28,653.84 26,474.39 24,290.85 22.103.21 19,911.48 17,715.63 15,515.67 13,311.58 11,103.36 8.891.00 6.674.49