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Required information [The following information applies to the questions displayed below.] A recent annual report for Celtic Alr Lines Included the following note: NOTE 1: SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Maintenance Costs We record malntenance costs related to our fleet in alrcraft malntenance materlals and outside repalrs. Malntenance costs are expensed as Incurred, except for costs Incurred under power-by-the-hour contracts, which are expensed based on actual hours flown. Modifications that enhance the operating performance or extend the useful lives of alfframes or engines are capitalized and amortized over the remalning estimated useful life of the asset or the remaining lease term, whichever is shorter. Assume that Celtic made extenslve repalrs on an alrplane engine, Increasing the fuel efficlency and extending the useful Iffe of the alrplane. The existing alrplane originally cost $4,500,000, and by the end of last year, It was half depreclated based on use of the straight-line method, a 20 -year estlmated useful life, and no residual value. During the current year, the following transactlons related to the alrplane were made: a. Ordinary repalrs and maintenance expenditures for the year, $740,000 cash. b. Extensive and major repalrs to the alrplane's engine, $2870,000 cash. These repalrs were completed at the end of the current year. c. Recorded depreclation for the current year. 2 What was the net book value of the alrcraft on December 31 of the current year