Smith Company showed the following amounts in its adjusted trial balance at 12/31/2020 related to factory equipment which was purchased on 1/1/2018: Debit Credit Equipment $58,000 Depreciation expense 10,000 Accumulated depreciation $36,000 If the company has been using the sum-of-the-years'-digits method for depreciation with $2,000 salvage value, what was the estimated useful life of the equipment? a. 5 years b. 6 years c. 7 years d. None of the above If the company has been using the units-of-production method for depreciation with no salvage value and the estimated useful life of 5,800 machine hours, for how many machine hours was the equipment used in 2020? a. 1,000 machine hours b. 2,600 machine hours c. 3,600 machine hours d. None of the above If the asset were sold on January 1, 2021 for $24,000, what effect did the sale have on the net income for 2021? a. The 2021 net income decreased by $2,000. b. The 2021 net income decreased by $3,000. c. The 2021 net income increased by $3,000. d. The 2021 net income increased by $2,000