A cube of wood whose edge is 12 mm is in equlibrium just submerged in a liquid with a layer of oil on top of the liquid as shown in the picture. The cube of wood has one of its faces parallel to the liquid surface. Determine the thickness of the layer of oil. The density of wood is 796 kg/m3, of the liquid 1296 kg/m3, and of the oil 606 kg/m3.