Microsoft's financial statements for the 2015 and 2014 fiscal years contained the following information: Balance Sheets ($ in millions) 2015 2014 Current assets: Accounts receivable, net of allowances for doubtful accounts of $ $ $723 and $644 16,722 14,546 Income Statements ($ in millions) Revenues 2015 2014 $ $ 148,701 132,656 In addition, the statement of cash flows disclosed bad debt expense of $1,435 million in 2015 and $1,051 million in 2014. Required: