i am so confused with this please help

Problem 9-2A In recent years, Avery Transportation purchased three used buses. Because of frequent turnover in the accounting department, a different accountant selected the depreciation method for each bus, and various methods were selected. Information conceming the buses is summarized as follows. Salvage Value Useful Life in Years Depreciation Bus Acquired Cost 98,300 118,000 88,640 Method 7,000 10,000 8,000 Straight-line Declining-balance Units-of-activity For the declining-balance method, the company uses the double-declining rate. For the units-of-activity method, total miles are expected to be 126,000, Actual miles of use in the first 3 years were 2016, 24,000; 2017, 31,500; and 2018, 30,000 For Bus # 3, calculate depreciation expense per mile under units-of-activity method. (Round answer to 2 decimal places, eg, 0.50.) Depreciation expense per mile Compute the amount of accumulated depreciation on each bus at December 31, 2017. (Round depreciation cost per unit to 2 decimal places, e.g. 0.50 and depreciation rate to o decimal places, e.g. 15%. Round final answers to 0 decimal places, eg, 2,125.) Accumulated depreciation BUS 1 BUS 2 BUS 3