i would like an explanation of how the coefficients of the products were calculated. "n-octane burned with 100% excess air with 15% of the carbon in the fuel forming carbon monoxide"

Analysis The combustion reaction for stoichiometric air is C8H18+12.5[O2+3.76N2]8CO2+9H2O+(12.53.76)N2 The combustion equation with 100% excess air and incomplete combustion is C8H18+212.5[O2+3.76N2](0.858)CO2+(0.158)CO+9H2O+xO2+(212.53.76)N2 The coefficient for CO is determined from a mass balance, O2 balance: 25=0.858+0.50.158+0.59+xx=13.1 Substituting, C8H18+25[O2+3.76N2]6.8CO2+1.2CO+9H2O+13.1O2+94N2