To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $2^{2}$ and $3$ is $12$. Multiply $\frac{\left(\sqrt{2}\right)^{2}}{2^{2}}$ times $\frac{3}{3}$. Multiply $\frac{4}{3}$ times $\frac{4}{4}$.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $12$ and $3^{2}$ is $36$. Multiply $\frac{3\left(\sqrt{2}\right)^{2}-4\times 4}{12}$ times $\frac{3}{3}$. Multiply $\frac{\left(2\sqrt{3}\right)^{2}}{3^{2}}$ times $\frac{4}{4}$.
Since $\frac{3\left(3\left(\sqrt{2}\right)^{2}-4\times 4\right)}{36}$ and $\frac{4\times \left(2\sqrt{3}\right)^{2}}{36}$ have the same denominator, add them by adding their numerators.
