To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x+2$ and $\left(x-3\right)\left(x+2\right)$ is $\left(x-3\right)\left(x+2\right)$. Multiply $\frac{3}{x+2}$ times $\frac{x-3}{x-3}$.
Since $\frac{3\left(x-3\right)}{\left(x-3\right)\left(x+2\right)}$ and $\frac{x^{2}+6x+4}{\left(x-3\right)\left(x+2\right)}$ have the same denominator, add them by adding their numerators.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x+2$ and $\left(x-3\right)\left(x+2\right)$ is $\left(x-3\right)\left(x+2\right)$. Multiply $\frac{3}{x+2}$ times $\frac{x-3}{x-3}$.
Since $\frac{3\left(x-3\right)}{\left(x-3\right)\left(x+2\right)}$ and $\frac{x^{2}+6x+4}{\left(x-3\right)\left(x+2\right)}$ have the same denominator, add them by adding their numerators.