Let $N$ be a minimal normal subgroup of a solvable finite group $G$. We know that $N$ is an elementary abelian $p$-group. Is it true that $dl(G/N)=dl(G)-1$?
Where $dl$ means derived length.
If it's false I would like a counterexample, if it is true a proof.
EDIT: as Arturo said, it's false. There are some additional conditions that make it true? For example if we add the contidion $G$ not abelian?