To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $\left(p+3\right)\left(p+4\right)$ and $\left(p+2\right)\left(p+3\right)$ is $\left(p+2\right)\left(p+3\right)\left(p+4\right)$. Multiply $\frac{1}{\left(p+3\right)\left(p+4\right)}$ times $\frac{p+2}{p+2}$. Multiply $\frac{2}{\left(p+2\right)\left(p+3\right)}$ times $\frac{p+4}{p+4}$.
Since $\frac{p+2}{\left(p+2\right)\left(p+3\right)\left(p+4\right)}$ and $\frac{2\left(p+4\right)}{\left(p+2\right)\left(p+3\right)\left(p+4\right)}$ 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 $\left(p+2\right)\left(p+3\right)\left(p+4\right)$ and $\left(p+2\right)\left(p+4\right)$ is $\left(p+2\right)\left(p+3\right)\left(p+4\right)$. Multiply $\frac{3}{\left(p+2\right)\left(p+4\right)}$ times $\frac{p+3}{p+3}$.
Since $\frac{3p+10}{\left(p+2\right)\left(p+3\right)\left(p+4\right)}$ and $\frac{3\left(p+3\right)}{\left(p+2\right)\left(p+3\right)\left(p+4\right)}$ have the same denominator, subtract them by subtracting their numerators.
