On January 1, 1999, a company purchased a machine that cost $12,000. It was depreciated for 1999, 2000, and 2001, using the straight-line method, on the basis of a 5 year estimated useful life and no residual value. During early 2002, the estimated total useful life was changed to 7 years with an $800 residual value at the end of year 7. (a) Give any entry required during 2002 to reflect the change (if none explain why). (b) Give the adjusting entry required on December 31, 2002.