Imagine that you have obtained spectra for several galaxies and have measured the observed wavelength of a hydrogen emission line that has a rest wavelength of 656.3 nanometers. here are your results:
galaxy 1: observed wavelength of hydrogen line is 660.0 nanometers.
galaxy 2: observed wavelength of hydrogen line is 665.8 nanometers.
galaxy 3: observed wavelength of hydrogen line is 682.7 nanometers.

a) calculate the redshift, z, for each of these galaxies.
b) from their redshifts, calculate the speed at which each of the galaxies is moving away from us using the
doppler formula. give your answers as a fraction of the speed of light.
c) estimate the distance to each galaxy from hubbleʹs law.