1) The document describes the simplest formula calculation for combustion of hydrocarbons in excess oxygen. It involves calculating the grams of carbon, hydrogen, and oxygen from the combustion products CO2 and H2O, then converting to moles and determining the ratios of each element. 2) The calculation shows combustion of 12.795g of hydrocarbon produces 32.689g of CO2 and 13.377g of H2O. From this the grams of C, H, and O are calculated. 3) Converting the grams of each element to moles and dividing the mole amounts by the smallest value gives molar ratios of 5:10:1 for C:H:O, yielding the simplest formula