The document shows a chemical ratio calculation to find the ratio of magnesium to oxygen in a compound. It calculates the ratio of the molar mass of magnesium, which is 24 g/mol, to the molar mass of oxygen, which is 16 g/mol. The ratio is simplified to 1.5, indicating there is 1.5 moles of magnesium for every 1 mole of oxygen in the compound.