Depreciation is computed primarily on a straight-line basis over the estimated useful lives of assets.

Net property was as follows (in millions) 

Automotive Sector	December 31, 2013	December 31, 2012
Land	$440	$423
Buildings and land improvements	10,325	10,249
Machinery, equipment and other	34,830	35,040
Software	2,069	1,813
Construction in progress	2,110	1,783
Total land, plant and equipment and other	49,774	49,308
Accumulated depreciation	(31,476)	(32,835)
Net land, plant and equipment and other	18,298	16,473

During 2013, Ford Motors sold property, plant, and equipment that cost $7,272 million and had $3,469 million in accumulated depreciation/amortization.

7.4 What is the average useful life of Ford Motor Company's amortizable assets for 2013?

		22.4 years
		23.59 years
		24.68 years
		25.25 years