Maertge Airlines purchases an aircraft for $84,000,000 on January 1, 2016. The residual value of the aircraft is estimated at $7,500,000, and its...

Maertge Airlines purchases an aircraft for $84,000,000 on January 1, 2016. The residual value of the aircraft is estimated at $7,500,000, and its useful life is estimated at 25 years. Applying the double-declining-balance method of depreciation, the depreciation expense recognized for the year ended December 31, 2018 will be __________.​

• ​$3,096,576
• ​$5,687,808
• ​$6,182,400
• ​$6,720,000