Astronomers observe the light from two distant galaxies, $G_1$ and $G_2$. Galaxy $G_2$ is located at three times the distance from Earth compared to Galaxy $G_1$ ($d_2=3d_1$), as shown in the diagram below.

If $v_1$ and $v_2$ are the recession velocities of the galaxies, and $\Delta {\lambda }_1$ and $\Delta {\lambda }_2$ are the shifts in wavelength of a specific spectral line observed from each galaxy, which of the following relations is correct? (Assume non-relativistic speeds where $v\ll c$.)