$ millions	Jan. 31, 2016	Feb. 01, 2015
Operating assets	$40,683	$38,573
Nonoperating assets	2,266	1,773
Total assets	42,949	40,346
Operating liabilities	15,043	13,552
Nonoperating liabilities	21,275	17,157
Total liabilities	36,318	30,709
Sales	89,234
Net operating profit before tax (NOPBT)	12,124
Nonoperting expense before tax	803
Tax expense	4,001
Net income	7,320

Compute net operating assets for the years ended January 31, 2016 and February 1, 2015. 2016 NOA $ 2015 NOA $