Sam & Sons Ltd. purchased machinery on September 30, 2023, at a total cost of $46,500. Sam estimated the useful life of the machinery to be eight years or 50,000 hours, with an estimated residual value of $3,500. The machinery was used for 5,000 hours in 2023 and 12,000 hours in 2024. Calculate amortization expense for 2023 and 2024 under each of the methods below. Round to the nearest dollar where necessary. Straight-line Double-declining-balance Units-of-production 2023 2024