Adjusting Allowance for Doubtful Accounts and Bad Debts Expense

Merck & Company reported the following from recent financial statements.

a$.$ Compute accounts receivable gross for each year.

b$.$ Determine the percentage of the Allowance for doubtful accounts to the gross Account receivables for each year. Round percentages to two decimal places.

What trend do we observe?

The allowance as a $\%$ of gross Accounts receivable is

Compute the four$-$year average. Round to two decimal places.