Question

hubble measured the velocity of the movement of galaxies by using
hubbles law states that galaxies located farthest from the center of the universe than those closest to the center.

Explanation:

1. For the first blank, Hubble used the Doppler effect (specifically redshift of spectral lines) to measure galaxy velocities; when an object moves away, its light shifts to longer (redder) wavelengths, which lets us calculate its recession velocity.
2. For the second blank, Hubble's law establishes a direct relationship between a galaxy's distance from us and its recession velocity: the farther a galaxy is, the faster it is moving away.

Answer:

1. First blank: the Doppler effect (spectral redshift)
2. Second blank: are moving away faster