Charles sold his 350 shares of stock for $11.25 a share. when his broker issued him the check for his sale of the stock the amount of the check was $3868.59. how much was the rate of commission that his broker charged him for the transaction

Charles made $3937.5 (calculate 350×$11.25=$3937.5).
If his broker passed a check with the amount of $3868.59, we can divide this by what was actually made on the sale. The result will be the percentage that Charles got from the sale. $3868.59÷$3937.5≈0.98
Charles got approximately 98,2% of what was sold. This means that his broker got as commission approximately 1,8%.