Answer:
Initially, he bought 700 shares per $9,29 each, so he lost:
payment = 700*$9.29 = $6503
The commision is $18, so the total lost is:
lost = $6503 + $18 = $6521
Now, when he sells, he sell each one to $9.90, so the earned is:
earned: 700*$9.90 = $6930
Then, the profit is the difference in those two quantities:
Profit = earned - lost = $6930 - $6521 = $409
The rate of return will be equal to $409/700 = $0.58, wich means that each share returs $0.58 in the lapse of a year.