Answer :
The salesperson earns a commission of $391
The total amount of merchandise that he sold is $2300
The commission rate is given by
[tex]r=\frac{\text{commission amount}}{\text{ sold amount}}[/tex][tex]r=\frac{\$391}{\$2300}=0.17[/tex]To convert the rate into percentage, multiply with 100%
[tex]r=0.17\cdot100=17\%[/tex]Therefore, the commission rate is 17%.