ill do a similar but different problem for you so you can get an idea.
"trader joes sell soy milk in a box-type container (rectangular prism to math folks). the container are 110mm wide, 188 mm long and 368 mm tall. the volume written on the package is given as a nice whole number of ounces. what volume measuremtn do you think is written on the package?"
okay so the volume of the package =11*18.8*36.8 ccc=7610.24cc
1cc=0.0338114023fl. oz.
7610.24cc=7610.24* 0.033814023fl.oz.=257.33oz=257oz
follow the exact stepes. if you can. its hard to explain while typing.