P6-42. Estimating Useful Life and Percent Used Up The property and equipment section of the Abbott Laboratories 2015 balance sheet follows. December 31 Property and equipment, at cost (S millions) 2015 2014 2013 727 868 Less: accumulated depreciation and amortization.. 2,383 12,632 12,870 . 6,6536,697 6 ,965 The company also provides the following disclosure relating to the useful lives of its depreciable asscts Property and Equipment-Depreciation and amortization are provided on a straight-line basis over the estimated useful lives of the assets. The following table shows estimated useful lives of property and equipment: Classification Estimated Useful Lives Equipment .3 to 20 years (average 11 years) During 2015, the company reported $871 on for depreciation expense Required a.Compute the estimated useful life of Abbott Laboratories' depreciable assets. How does this compare with its useful lives footnote disclosure above? b.Compute the estimated percent used up of Abbott Laboratories' depreciable assets. How do you in- terpret this figure