Calhoun, Inc. purchased equipment at the beginning of 2015 for $180,000. Calhoun decided to depreciate the equipment over a 5-year period using the double-declining-balance method. Calhoun estimated the equipment's residual value at $30,000. Which of the following statements is correct concerning Calhoun's financial statements at December 31, 2015?

The book value of the equipment is $72,000.

The book value of the equipment is $108,000.

The total accumulated depreciation is $90,000.

Depreciation expense for 2015 is $60,000.