To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $a-4$ and $a+4$ is $\left(a-4\right)\left(a+4\right)$. Multiply $\frac{a+4}{a-4}$ times $\frac{a+4}{a+4}$. Multiply $\frac{a-4}{a+4}$ times $\frac{a-4}{a-4}$.
Since $\frac{\left(a+4\right)\left(a+4\right)}{\left(a-4\right)\left(a+4\right)}$ and $\frac{\left(a-4\right)\left(a-4\right)}{\left(a-4\right)\left(a+4\right)}$ have the same denominator, subtract them by subtracting their numerators.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $4$ and $a$ is $4a$. Multiply $\frac{1}{4}$ times $\frac{a}{a}$. Multiply $\frac{1}{a}$ times $\frac{4}{4}$.
Multiply $\frac{16a}{\left(a-4\right)\left(a+4\right)}$ times $\frac{a+4}{4a}$ by multiplying numerator times numerator and denominator times denominator.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $a-4$ and $a+4$ is $\left(a-4\right)\left(a+4\right)$. Multiply $\frac{a+4}{a-4}$ times $\frac{a+4}{a+4}$. Multiply $\frac{a-4}{a+4}$ times $\frac{a-4}{a-4}$.
Since $\frac{\left(a+4\right)\left(a+4\right)}{\left(a-4\right)\left(a+4\right)}$ and $\frac{\left(a-4\right)\left(a-4\right)}{\left(a-4\right)\left(a+4\right)}$ have the same denominator, subtract them by subtracting their numerators.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $4$ and $a$ is $4a$. Multiply $\frac{1}{4}$ times $\frac{a}{a}$. Multiply $\frac{1}{a}$ times $\frac{4}{4}$.
Multiply $\frac{16a}{\left(a-4\right)\left(a+4\right)}$ times $\frac{a+4}{4a}$ by multiplying numerator times numerator and denominator times denominator.