26. True or False: Firms generally prefer to have a positive working capital (current assets - current liabilities). a. True b. False 27. True or False: Purchasing direct materials on account (i.e. buy now, pay later), all else equal, would decrease a firm's ROI (NOI/average operating assets). a. True b. False 28. True or False: All else equal, an increase in the cost of sales commissions would decrease both a firm's gross profit margin \% (Gross Margin/Sales) and a firm's net profit margin \% (Net Income/Sales). a. True b. False