2.5 pts Question 6 Hallie purchased new machinery for $100,000 that has an estimated useful life of 5 years and a salvage value of $10,000. Hallie uses the double-declining balance method of depreciation. What is the net book value of the machinery at the end of year 2? O a. $36,000 O b. $42.400 c. $60,000 O d. $64.000 e. None of the above