Gives $0.7938\,g\,CO _{2}=0.018$ moles

$0.4428\,g\,H _{2} O =0.0246$ moles

So moles of $C =0.018 \Rightarrow 0.216\,g$

Moles of $H =0.049 \Rightarrow 0.049\,g$

$\therefore$ wt. of Oxygen $=0.492-0.216-0.049$

$\%$ of Oxygen $=\frac{0.227}{0.492} \times 10046$ (approx.)