Answer
800 fluid ounces
Work Step by Step
6 $\frac{1}{4}$ gal = fl oz.
Use the unit fraction $\frac{4 quarts}{1 gal}$ to change gallon to quarts, next use the unit fraction $\frac{2 pint}{1 quart}$ to change quart to pint, now use the unit fraction $\frac{2 cup}{1 pint}$ to change pint to cup and last use the unit fraction $\frac{8 ounces}{1 cup}$ . Notice how all the units divide out except cup, which is the unit you want in the answer.
$\frac{25}{4}$ gal * $\frac{4 quarts}{1 gal}$ * $\frac{2 pint}{1 quart}$* $\frac{2 cup}{1 pint}$ * $\frac{8 ounces}{1 cup}$ = 800 fluid ounces.