On January 1, 2019, Bithe Smarney & Co. purchased $35,500 worth of office equipment with an estimated useful life of seven years and an estimated residual value of $4,000. Bithe Smarney uses the straight-line method of amortization for all office equipment. At the beginning of 2022, Bithe Smarney revised its estimate of the useful life of the office equipment to a total of eight years. The 2022 amortization expense is: $3,600. $4,400. $2,000. $3,000.