To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $m\left(m-1\right)$ and $m-1$ is $m\left(m-1\right)$. Multiply $\frac{1}{m-1}$ times $\frac{m}{m}$.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $m\left(m-1\right)$ and $m-1$ is $m\left(m-1\right)$. Multiply $\frac{1}{m-1}$ times $\frac{m}{m}$.