G Thunberg Inc. were able to buy on the black market a used internal-combustion engine for $8,000 and estimates its useful life is 10 years. Using a $600 salvage value, determine the following: 1. The amount of annual straight-line depreciation. [2] 2. The amount of depreciation for the sixth year computed by the double declining balance method. [4] 3. The amount of depreciation for the sixth year computed by the sum-of-years'-digits method. [4]