We have to calculate the rate of commission of the total sales amount. We know that the total sales amount is $38,642.00 and it represents 100%. A salesman received $2,704.94 in commission and it represents x%. The proportion is: 38,624.00 : 2,704.94 = 100 : x; 38,624.00 x = 270,794 ; x = 270,794 : 38,624; x = 7% . Answer: His rate of commission is .07 or 7%.