thank you for your reply firstly. i still can’t understand it. The question in year09. the total estimated profit including the plant (8000.it’s the initial cost and no depreciation charges) However in year10.the plant (12000-3000? why not use the initial cost ?) sorry .I get it seemingly a little… removing 3000 just due to the residual value?and the residual value shouldn’t be recorded in? right ? I am very sorry to waste your time. thanks !