How to create a report that displays Return on Investment for stock purchased and sold

Return on investment is shown in the 'Stock Turn Summary' report. This report is located under 'Reports Menu'/'Sales Reports'/'SAL007 - Stock turn summary'.

The columns shown are Department, Total Sales ($), % Total, No. of Sales, % Total, Avg. Sale ($), Total Cost ($), Avg. Days to Sell, Qty. in Stock, Closing Stock Cost, % Total Stock, Gross Profit ($), GP Margin (%), % Total GP, Avg. Markup, ROI [Return on Investment], Stock Turn. The report can be sorted by department, supplier or category.