The property and equipment footnote fro Property and Depreciation A summary of property and equipment at October 31 follows. Property and Equipment (5 millions) Useful Lives (Years) 2015 2014 Land $114 $120 Buildings and building equipment 23 3,682 3,037 Machinery and equipment 11 5.721 5,089 Dies, patterns, tools, etc. 8 1,567 1,552 5 875 889 345 530 Total at cost 12.304 11.217 5,846 5,694 Total $6,458 $5,523 All other Construction in progress Less accumulated depreciation *Weighted averages Total property and equipment additions in 2015, 2014 and 2013 were $666 million, $1,016 million and $1,15 a. Compute the average useful life of Deere's depreciable assets at year-end 2015. Round answer to one decimal place. 17.8 years b. Estimate the percent used up of Deere's depreciable assets at year-end 2015. Round answer to one decimal place (ex: 0.2345 = 23.5%) 54.5