The area (in sq. units) of the region

The area (in sq. units) of the region

$\begin{aligned} A=&\{(x, y) \in R \times R \mid 0 \leq x \leq 3,0 \leq y \leq 4\\ &\left.y \leq x^{2}+3 x\right\} \text { is : } \end{aligned}$