Solution
Start by guessing Pearl didn't
sell enough to garner any salary from the bonus commission rate. Salary made from commission = Total salary 
monthly base salary = $4000  $1500 = $2500 Commission rate × Amount eligible for
commission rate = Amount earned from commission = Rate × Amount = Salary
Amount = Salary ÷ Rate = $2500 ÷ (9 /
100) = $27778 So presuming no bonus commission is made, Pearl would have to sell $21000 + $27778 = $48778 Since the guessed amount sold is more than
the required quota for obtaining bonus commission, our guess was wrong and we
know that Pearl sold at least the required quota for
obtaining bonus commission which is $30000. Amount made from commission for sales below
$30000 = Amount below $30000
eligible for normal commission × normal commission rate = $9000 ×
9 / 100 = $810 Amount left to make from bonus commission =
Total salary  monthly base salary  amount made from normal commission for
sales below $30000 = $4000 
$1500  $810 = $1690 Total commission percentage rate for sales over
$30000 = normal commission percentage rate +
bonus commission percentage rate = 9% +
2% = 11% Again for the money made from bonus commission,
Amount = Salary / Rate = $1690 / (11 / 100) =
$15364 Total amount sold = monthly quota +
amount sold at only normal commission + amount sold at bonus commission =
$21000 + $9000 + $15364 = $45364
