The answers in red are all correct, I would just like a thorough explanation on why the given solutions are correct.

Lone Star Overnight (LSO) is considering buying 20 new delivery trucks to expand its business. Each truck costs $20,000 and can be depreciated over a straight line basis over 10 years. The increase in operating profits from these additional delivery trucks is $240,000 dollars a year. Assume there are no additional costs to operating these trucks. A. What is the annual depreciation and book value for these trucks for the first 4 years? (5 points) Year 0 1 2 3 4 Depreciation 40,000 40,000 40,000 40,000 Book Value 400,000 360,000 320,000 280,000 240,000