ROI stands for Return on Investment, which is a method to measure the performance of an investment. To calculate your profit, take the the total return on investment and subtract the cost of the investment. To calculate that as a percentage, take the net profit and divide it by the cost of the investment.

Example:
$100,000 total investment cost
$120,000 total return
Profit = $120,000 – $100,000 = $20,000
ROI in Percentage = $20,000 / $100,000 = 20% ROI