A German fuel blend called Reichkraftskoff is made up of $50\%$ motor benzole $(75\%$ benzene, $15\%$

toluene, $10\%$ xylene$),25\%$ tetralin $),$ and $25\%$ industrial alcohol $(80\%$ ethanol, $20\%$ methanol$).$

After combustion in excess air, a stack gas containing $9\mathrm{.}13\%C{O}_2$ and $1\mathrm{.}83\%CO$ is obtained. Calculate:

a$)\%$ excess air

$(50\%)$

b$)$ complete orsat analysis of the stack gas $(8\mathrm{.}09\%O_2,80\mathrm{.}95\%N_2)$