In the equation provided, the total earnings of the salesman can be expressed as \( 2000 + 0.1s \) dollars, where \( s \) represents his sales total in dollars.
- The term \( 2000 \) represents a fixed amount that he earns each month, regardless of his sales.
- The term \( 0.1s \) represents his commission, which is 10% of his total sales.
Therefore, the \( 2000 \) in the equation represents his monthly base salary in dollars.
So the correct answer is:
his monthly base salary in dollars.