Thermodynamics

$$\begin{aligned} & \text { If } \mathrm{C}(s)+\mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g), \Delta H=-X \\ & \mathrm{CO}(g)+\frac{1}{2} \mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g), \Delta H=-Y \end{aligned}$$ Calculate $\Delta_f H$ for $\mathrm{CO}_{(g)}$ formation