How do I do part c?

Dulaney's Stores has posted the following yearly earnings and expenses. Click the icon to view the yearly data. a. Dulaney's current profit margin is Dulaney's current yearly ROA is \%. (Enter your response rounded to one decimal place.) \%. (Enter your response rounded to one decimal place.) b. Suppose COGS and merchandise inventory were each cut by 20%. The new pretax profit margin is \%. (Enter your response rounded to one decimal place.) The new ROA is \%. (Enter your response rounded to one decimal place.) c. Based on the current profit margin in part a., Dulaney would have to generate $ in additional sales in order to have the same effect on pretax earnings as a 20% decrease in merchandise costs. (Enter your response rounded to the nearest dollar.) \begin{tabular}{ll} \hline Earnings and Expenses (Year Ending January 2012) \\ \hline Sales & $41,000,000 \\ Cost of goods sold (COGS) & $21,000,000 \\ Pretax earnings & $3,731,000 \\ \hline Selected Balance Sheet Items & \\ \hline Merchandise Inventory & $1,865,500 \\ Total assets & $7,000,000 \\ \hline \end{tabular}