$0.3g\quad\quad\quad\quad\quad\quad\quad\quad0.2g\quad\quad\quad0.1g$

$\frac{ n _{ CO _{2}}}{ n _{ H _{2} O }}=\frac{ x }{ y / 2}=\frac{0.2 / 44}{.1 / 18}$

$\frac{2 x }{ y }=\frac{36}{44}=\frac{9}{11}$

$x =\frac{9 y }{22}$

$\frac{ n _{ C _{ x } H _{ y } O_{ z } }}{ nCO _{ 2 } }=\frac{1}{ x }$

$\frac{0.3 }{12 x + y +16 z } \times \frac{44}{0.2}=\frac{1}{ x }$

$66 x =12 x + y +16 z$

$54 x = y +16 z$

$\frac{54 \times 9 y }{22}- y =16 z$

$\frac{464 y }{22}=16 z$

$z =\frac{29 y }{22}$

$C _{ x } H _{ y } O _{z}= C _{ x } H _{ y } O _{z}$

$C _{\frac{9 y}{22}} H _{ y } O _{\frac{29 y}{22}}^{22}$

$C _{9} H _{22} O _{29}$

$\,\%$ of $C =\frac{12 \times 9}{(12 \times 9+22+29 \times 16)} \times 100=\frac{108}{594} \times 100$

$18.18 \,\%$