Please explain it

Extra Exercise on Depreciation Calculate the present worth of the ATCF. Is this still a good investment after tax? Use MACRS- GDS half year convention (equipment is in the 7 years property) and it is disposed at year 6. Investment Units sold per year Selling price per unit Cost per unit MV Study period MACRS-GDS Tax BTMARR $125,000 2000 units $50 $10 $40000 6 years 7 years 40% 15%