Let $H\trianglelefteq G$ and $S$ a Sylow $p-$subgroup of $G$, then
$H\cap S$ is a Sylow $p-$subgroup of $H$.
$\frac{HS}{H\cap S}$ is a Sylow $p-$subgroup of $\frac{G}{H}$.
I already have the proof of the first statement (with the help of this site). I have questions on the second.