Let $\phi:G\to H$ be a homomorphism of groups.
Under what conditions does
$\frac{G}{ker (\phi)} \simeq im(\phi)$ imply there exists an isomorphism
$G\simeq im(\phi) \oplus ker(\phi)$, and why?
The answers in the possible duplicate question are not sufficient for me, as I do not have an understanding of category theory or exact sequences. I'm looking for a detailed answer that makes use of basic group theory alone. In particular I am interested in knowing if $G$ or $H$ being abelian makes any difference.