Explanation:
Fgravity = G*(mass1*mass2)/D²
G is the gravitational constant throughout the universe.
D is the distance between the 2 objects.
now the distance is tripled. that means
Fgravitynew = G*(mass1*mass2)/(3D)² =
= G*(mass1*mass2)/(9D²) =
= (G*(mass1*mass2)/D²) / 9 = Fgravity/9
so, the new force of attraction is 18/9 = 2 units.