Answer:
12000
Step-by-step explanation:
Straight-line method of Depreciation = Cost - Salvage value
Year 1 useful life
Depreciation year 1 = 18000-3000
5years
Depreciation Year 1 =15000÷5
dep year 1 = 3000 , ( in straight line method depreciation remains constant in all the years)
Net Book Value year 1 = (18000-3000) = 15000
Dep Year 2 = 3000 , NBV= (15000-3000) = 12000
Beginning of ?Year 3 NBV = 12000