Context-free Grammar Exercise Could someone explain me how to form a context-free grammar with all rules R by this example language, please? 
\begin{equation}
L:=\left\{w c v c \overleftarrow{w} | w, v \in\{a, b\}^{+}\right\}
\end{equation}
The arrow over w means, that the word w is written backwards.

I already know that \begin{equation}
\Sigma=\{a, b, c\}
\end{equation}
and V (non terminal symbols) maybe have to be \begin{equation}
V=\{S, A, B, C\}
\end{equation}

Thank you for helping.
I think you can solve this using this construct:

$$S \rightarrow ASA|BSB|ATA|BTB $$
$$T \rightarrow CAZC|CBZC$$
$$Z \rightarrow AZ|BZ|\epsilon$$
$$A \rightarrow a , B \rightarrow b, C \rightarrow c$$

First rule provides the $w$ and $w^R$ in the language, second rule makes sure $v \ge 1$ and has 1 c in both sides and third is just constructing the $v$ further. My assumption was your arrow on top of last $w$ was just meant it is reversed.