To earn additional income, Heather took up a part-time job at a call center in the evenings and weekends, here, she receives a base salary of $750 per month plus commission. Her commission rate is 5% on the first $5000 in sales above her monthly quota of $10,000 and 7.5% on any additional sales thereafter.

e) What single commission rate would have resulted in the same amount of commission earned?