In recent years, Monty Transportation purchased three used buses. Because of frequent turnover in the accounting department, a different accountant was in charge of selecting the depreciation method for each bus, and various methods have been used. Information concerning the buses is summarized in the table below. Bus Acquired Cost Salvage Value Useful Life in Years Depreciation Method 1 Jan. 1, 2020 $96,000 $6,500 5 Straight-line 2 Jan. 1,2020 122,000 12,000 5 Declining-balance 3 Jan. 1.2021 93,000 9,000 4 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 120.000. Actual miles of use in the first 3 years were 2021. 24,000; 2022, 35,500; and 2023, 32,000. (a1) For Bus #3, calculate depreciation expense per mille under units-of-activity method. (Round answer to 2 decimal places, eg. 0.50) Depreciation expense $ per mile