Velocities  Distances ?

All of the distances in the previous slides were derived from the measured velocities (which were derived from the Doppler shifts of the spectral lines)
It was Edwin Hubble that figured out that the velocities represented the distances to the objects
So how did Hubble figure this out?

All of the distances in the previous slides were derived from the measured velocities (which were derived from the Doppler shifts of the spectral lines)