GHI Ltd acquired a building for $1,000,000 on January 1st, 2023. The building has an estimated useful life of 40 years and a residual value of $100,000. Calculate: a) Annual straight-line depreciation expense. b) Accumulated depreciation at the end of the second year. c) Book value of the building at the end of the third year. d) Gain or loss if the building is sold for $900,000 at the end of the third year.