3. The operating costs and scrap values of an equipment planned to be purchased by years are given in the table below. The cost of the equipment is 10 000 TL and the annual interest rate to be used in the calculation is 10%. What is the economic service life of the equipment? (EH can be determined after calculating the annual value for the 3rd year) operating cost scrap value annual value dollar/year 1 -1000 7000 -5000 21 -1200 5000 -4476 31 -1300 4500 4| -2000 3000 -3847 5| -3000 2000 -3921