To set up the inequality based on the problem statement, we need to translate the condition into mathematical terms. The problem states that the sum of 4.5 and one-third of a number \( n \) is equal to at most 38.9. This can be expressed as:
\[ 4.5 + \frac{1}{3}n \leq 38.9 \]
This inequality represents all the possible values of the number \( n \). Therefore, the correct response is:
\(\frac{1}{3}n + 4.5 \leq 38.9\), where \( n \) is equal to the number.
This can also be simplified by isolating \( n \) if needed, but the inequality itself is correctly stated as given above.