Answer
$36$.
Work Step by Step
By using Theorem 1, we have $$
\operatorname{Area}(G(\mathcal{D}))=|\operatorname{Jac}(G)| \operatorname{Area}(\mathcal{D})
$$
And thus
$$
\operatorname{Area}(G(\mathcal{R}))=|\operatorname{Jac}(G)| \operatorname{Area}(\mathcal{R})=4\times 9=36.
$$
