Chemical Kinetics

For the reaction \(\mathrm{N}_{2(\mathrm{~g})}+3 \mathrm{H}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{NH}_{3(\mathrm{~g})}\),
what is the relation between \(\frac{\mathrm{d}\left[\mathrm{N}_2\right]}{\mathrm{dt}}\) and \(\frac{\mathrm{d}\left[\mathrm{H}_2\right]}{\mathrm{dt}}\) ?