Statement "If G is finite abelian group and H is its subgroup then there is a normal subgroup N of G such that G/N is isomorphic to H ."
Clearly [G:H] divides order of G .As G is abelian therefor there exists a normal subgroup of order [G: H] ( Say N). Now o (G)/o (H)=o (N) . I.e o (G)/o (N) =o (H) but How can I prove above statement?