Curt can be paid in one of two ways for the furniture he sells. Plan A: Salary of $800 per month, plus a commission of 10% of sales. Plan B: Salary of $1200 per month, plus a commission of 15% of sales in excess of $8000. For what amount of monthly sales is plan B better than plan A, assuming Curt's sales are always more than $8000? lebook .