Your company is considering the purchase of a second-hand scanning microscope at a cost of$10,500, with an estimated salvage value of $500 and a projected useful life of four years. 

1. 
   
2. Instructions
3. Determine the straight-line (SL), and sum of years digits (SOYD) depreciation schedules. 
4. Also, calculate net book value at the end of 3rd year when using the two methods.