I think a) would be the answer. I proceeded by elimination: the domaine of the function goes from 3 and continues to infinity, so that leaves with a) and b) as possible answers. Both have the same range and both of their functions reflect over the x axis, so we have to compare the two answer by looking at the position of the function in the graph. The function is in the first quadrant (top right corner), so the position of the function has to be at our right, which leads us to a).
Given:
Lamont cotton is 4% commission on the first 10,000 of monthly sales and 10% on all sales over 10,000.
Consider his last month sales is 38,000.
To find:
The total commission.
Solution:
4% commission on the first 10,000 of monthly sales is

Sales over 10,000 is

10% commission on all sales over 10,000 is

Now, the total commission is

Therefore, the total commission is 3,200.