Martin Company purchases a machine at the beginning of the year at a cost of $70,000. The machine is depreciated using the straight-line method. The machine's useful life is estimated to be 4 years with a $4,000 salvage value. The book value of the machine at the end of year 4 is: Muitiple Choice $16,500. $66,000 $35,000 $4,000. $0