The density of a certain material is such that it weighs 4 kilograms for every 9 cups of volume. Express this density in ounces per gallon.

4 kg = 141.1 oz. I looked that up on the web.

9 cups = 0.5625 gallons. I looked that up on the web.
density = mass/volume 141.1 oz/0.5625 gal = ?