For the combustion reaction: C7H14 + 10.5 O2 + 39.48 N2 7CO2 + 7H2O + 39.48 N2 (atomic weight C = 12, H = 1, O = 16, N = 14), the stoichiometric air to fuel (A/F) ratio (mass basis) is: (If the ratio is 10 to 1, report as 10, not 10:1, or 10/1).