The percent markdown can be calculated using the formula:
\[ \text{Percent Markdown} = \frac{\text{Original Price} - \text{Current Price}}{\text{Original Price}} \]
In this case, the original price is $28,500 and the current price is $25,875. The ratio that represents the markdown can be expressed as:
\[ \frac{28,500 - 25,875}{28,500} \]
This simplifies to:
\[ \frac{2,625}{28,500} \]
Thus, the fraction that can be used to calculate the percent markdown is:
\[ \frac{2,625}{28,500} \]