Chemical Kinetics

If Instantaneous rate of reaction is stated as $-\frac{1}{2} \frac{\mathrm{~d}[x]}{\mathrm{dt}}=-\frac{\mathrm{d}[\mathrm{y}]}{\mathrm{dt}}=\frac{1}{2} \frac{\mathrm{~d}[\mathrm{z}]}{\mathrm{dt}}$, identify the reaction.