Depreciation by units-of-activity method Prior to adjustment at the end of the year, the balance in Trucks is $296,900 and the balance in Accumulated Depreciation—Trucks is $99,740. Details of the subsidiary ledger are as follows:etermine the depreciation rates per mile and the amount to be credited to the depreciation section of each of the subsidiary accounts for the miles operated during the current year. Round the rate per mile to two decimal places.