Explanation:
Fgravity = G*(mass1*mass2)/D²
G is the gravitational constant, which has the same value throughout our universe.
D is the distance between both objects.
so, now some numbers change
Fgravitynew = G*((1/3)*mass1*2*mass2)/(2D)² =
= G*((2/3)*mass1*mass2)/(4D²) =
= (2/3)* (G*(mass1*mass2)/D²) / 4 =
= ((2/3)/4) * G*(mass1*mass2)/D² =
= (2/12) * Fgravity = Fgravity/6
the new gravitational force will be 16/6 = 8/3 units.