Calculate the stochiometric air fuel ratio for complete combustion

Question

A sample bituminous coal gave the following ultimate analysis by mass:

Carbon  –  81.9%,

Hydrogen  –  4.9%

Oxygen  –  6%,

Nitrogen  –  2.3% and Ash  –  4.9%

          Calculate,

i.    the stochiometric air fuel ratio for complete combustion and

ii.   the volumetric analysis of wet and dry products of combustion when the air supplied is 25% in excess of that required for complete combustion.