4) SD Co. acquired a piece of equipment on January 1, 2021 for $13 million. The equipment is expected to have a useful life of 18 years, have a salvage value of $1 million, and will be capable of producing 300 million units of the product. The equipment produced 18.6 million units and 19.5 million units in 2021 and 2022, respectively.

Given the above information, calculate current year depreciation and net book value of the equipment at 12/31/2022 based on as many depreciation methodologies as you can. Assume that the company uses double the normal rate for any accumulated methods. Bonus: Calculate based on a 4^th method not in the text/slides but discussed in class.