The salespeople at a local car dealership are paid a commission based on the profit earned from each car they sell. If the profit is less than $900, the salesperson gets 15% of the profit as commission. If the profit on the car is equal to or between $900 and $1,500, the salesperson gets 17% of the profit. Even better, if the profit on the car sold is more than $1,500, the salesperson gets 21% of the profit as commission. Describe the graph that shows the commission earned by a salesperson as a function of the profit earned, including endpoints and whether they are empty or closed circles.