  We discuss in the context of finite extensions two classical theorems of
Takahasi and Howson on subgroups of free groups. We provide bounds for the rank
of the intersection of subgroups within classes of groups such as virtually
free groups, virtually nilpotent groups or fundamental groups of finite graphs
of groups with virtually polycyclic vertex groups and finite edge groups. As an
application of our generalization of Takahasi's Theorem, we provide an uniform
bound for the rank of the periodic subgroup of any endomorphism of the
fundamental group of a given finite graph of groups with finitely generated
virtually nilpotent vertex groups and finite edge groups.
