Parties may agree on different profit ratios for different permitted situations.
• Wheat trade may give one ratio.
• Flour trade may give another.
• Business in the home town may have one ratio.
• Business in another town may have another.
The conditions must be known and agreed in advance.
Rent is justified by use of an owned share, so it should track the ownership that actually remains with the lessor. If ownership falls, the rentable share also falls.