To convert the volume from milliliters to liters, you can use the conversion ratio:
1 liter = 1,000 milliliters.
To find out how many liters 6,750 milliliters is, you can divide the volume in milliliters by the number of milliliters in a liter:
\[ \text{Liters} = \frac{6,750 \text{ milliliters}}{1,000 \text{ milliliters/liter}} = 6.75 \text{ liters}. \]
So, the answer is 6.75.