a. For each year, calculate the percentage of account receivables written off out of total credit sales. b. For each year, calculate the percentage of account receivables written off in each category of outstanding receivable age (think about which dates are relevant when assigning the categories of aging receivables). c. Collect the data for years 2013-2017 (total outstanding receivables, percentage of receivables written off relative to credit sales, and the percentage of receivables written off in each aging category of outstanding receivables), and fill in the table in the Solution worksheet.