When we need to multiply a number by a percentage, it is helpful to convert the percent number to a fraction or a decimal number. Let's convert the percent to a fraction. 13.5% is equal to the fraction (13.5 / 100). We need to multiply the monthly sales by this fraction to find the commission. commission = ($4,230.00) X (13.5 / 100) = $571.05 Her monthly commission is $571.05 We can check that this is the correct answer. ($571.05) / ($4230.00) = 0.135 which is equal to 13.5% 13.5% is the the correct rate of commission, so it seems that our answer is correct.