Grammar Representation
\[\begin{aligned}
\langle expr \rangle &\;\to\; \langle expr \rangle \; \texttt{+} \; \langle term \rangle
\;\mid\;
\langle expr \rangle \; \texttt{-} \; \langle term \rangle
\;\mid\;
\langle term \rangle,\\[4pt]
\langle term \rangle &\;\to\; \langle term \rangle \; \texttt{*} \; \langle factor \rangle
\;\mid\;
\langle term \rangle \; \texttt{/} \; \langle factor \rangle
\;\mid\;
\langle factor \rangle,\\[4pt]
\langle factor \rangle &\;\to\; \texttt{(} \; \langle expr \rangle \; \texttt{)}
\;\mid\;
\texttt{num}
\;\mid\;
\texttt{id}.
\end{aligned}\]