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.