Answer: The new force will be 72.0 units.
Explanation: The gravitational force between two objects can be written as:
F = G*m1*m2/r^2
Where G is the gravitational constant, m1 and m2 are the masses of both objects and r is the distance between them.
Now, we have that F = 18.0 units.
Now, supose that we change r to r/2, the new force is:
F' = G*m1*m2/(r/2)^2 = 4*G*m1*m2/r^2 = 4*F = 4*18.0 units = 72.0 units
