Answer:
16.67%
Explanation:
To calculate David's ROI (Return on Investment) from buying and selling the stock, you can use the following formula:
ROI = (Sale price - Purchase price) / Purchase price
Plugging in the values for the sale price ($10.50 per share) and the purchase price ($9.00 per share) gives us:
ROI = ($10.50 - $9.00) / $9.00
= $1.50 / $9.00
= 16.67%
Therefore, David's ROI from buying and selling the stock was 16.67%. This means that his investment returned a profit of 16.67% of the amount he invested.