Final answer:
The annual depreciation expense for the machine purchased by Woodstock, Inc. is $6,000 using the straight-line depreciation method.
Step-by-step explanation:
The annual depreciation expense for Woodstock, Inc.'s machine using the straight-line depreciation method can be calculated as follows:
Total Cost of Machine = Cost of Machine + Transportation and Installation
Total Cost of Machine = $40,000 + $1,000 = $41,000
Depreciable Amount = Total Cost of Machine - Residual Value
Depreciable Amount = $41,000 - $5,000 = $36,000
Annual Depreciation Expense = Depreciable Amount / Useful Life of the Machine
Annual Depreciation Expense = $36,000 / 6 years = $6,000
Therefore, the correct answer is b. $6,000.