Using line depreciation method,
Depreciable cost = Cost - Salvage value = $40,900,000- $4,090,000 = $36,810,000
Depreciation per year = Depreciable cost/life = 36,810,000/15 = $2,454,000
After third year of use,
Depreciation expenses = $,2,454,000*3 = $7,362,000
Book value = cost - depreciation expenses = 40,900,000 - 7,363,000 = $33,538,000