The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are x, y and z. The sum of x, y and z is \ \ \ \. Na_4[ Fe ( CN )_5(…

The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are $\displaystyle x, y$ and $\displaystyle z$. The sum of $\displaystyle x, y$ and $\displaystyle z$ is \_\_\_\_. $$\begin{array}{ccc} \mathrm{Na}_4\left[\mathrm{Fe}(\mathrm{CN})_5(\mathrm{NOS})\right] & \mathrm{Na}_4\left[\mathrm{FeO}_4\right] & {\left[\mathrm{Fe}_2(\mathrm{CO})_9\right]} \\ \text { (A) } & \text { (B) } & \text { (C) } \end{array} $$