Two point charges +q and +4q separated by a distance d in vacuum exert a force F on each other. The arrangement is modified in three successive steps:
(i) the distance between them is increased to 3d,
(ii) the larger charge is reduced to 34q, and
(iii) the system is immersed in a medium of relative permittivity 2.
Calculate the final force between the charges in terms of the original force F.