To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x$ and $y$ is $xy$. Multiply $\frac{x-y}{x}$ times $\frac{y}{y}$. Multiply $\frac{y-x}{y}$ times $\frac{x}{x}$.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x$ and $y$ is $xy$. Multiply $\frac{x-y}{x}$ times $\frac{y}{y}$. Multiply $\frac{y-x}{y}$ times $\frac{x}{x}$.