$N$ be a closed vector subspace of a vector space $L$

$N$ be a closed vector subspace of a vector space $L$

I am not able to do the following , could anyone help me?
$N$ be a closed vector subspace of a vector space $L$ such that $L/N$
finite dimensional, we need to show that any subspace of $L$ containing
$N$ is closed.
Thank you.