Stephan's accounts receivable financial data (in millions) for three years are listed below: 2019 2018 2017 Sales $159,600 $183,050 $139,300 4,950 5,460 4,350 Gross accounts receivable Allowance for doubtful accounts 360 300 330 Required: a. Calculate the net value of receivables that will be reported on Stephan's balance sheet for each year. b. Determine the accounts receivable turnover for 2019 and 2018. c. Compare the accounts receivable turnovers for 2019 and 2018 and comment on the differences