Sales Options

A company offers two options for sales partners: $150 plus a 6 percent commission weekly or a flat 11 percent commission. Mrs. Lee, the top salesperson in the company, averages $3500 a week in sales. Which option should she take, and why?

(Source: Mathematics Teaching in the Middle School, May 1998)

Extension:
Flat commissions are rewarding if sales partners make enough sales. What is the minimum weekly average for sales that Mrs. Lee needs in order for Option 2 to give her more money than Option 1.