Redox Reactions

In the following redox reaction, what will be the sum of $x, y$, and $z$ ?

$$ \begin{aligned} x \mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q) & +y \mathrm{SO}_3^{2-}(a q)+z \mathrm{H}^{+}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{SO}_4^{2-}(a q)+\mathrm{H}_2 \mathrm{O}(l) \end{aligned} $$