*Please explain how you solved each one*

21. On January 1, 2005, the Edith Company purchased a piece of machinery that costs $150,000 and is expected to have a salvage value of $10,000 and a useful life of 7 years. Using straight-line depreciation, the book value of the machinery at December 31, 2007 would be a $60,000 b. $70,000 c. $80,000 d. $90,000 e. $100,000 22. On January 1, 20X5, Button Manufacturing Company purchased a machine for $39,980, and expects to use the machine over the next four years. Button set the residual value on the machine at $3,500. What is the depreciation expense in 20X6 if Button uses the double-declining balance method of depreciation? a $6,875 b. $6,000 c. $9,995 d. $12,000 e. $15,000