Buhner Company constructed a building at a cost of 3,000,000 and occupied it beginning in January 1990. It was estimated at that time that its life would be 40 years, with no salvage value. In January 2010, a new roof was installed at a cost of $500,000 (paid in cash), and it was estimated then that the building would have a useful life of 25 years from that date. The cost of the old roof was $200,000. a) What amount of depreciation should have been charged annually from the years 1990 to 2009? (Assume straight-line depreciation.) b) What entry should be made in 2010 to record the replacement of the roof? co Prepare the entry in January 2010, to record the revision in the estimated life of the building, if necessary