1. The problem is to simplify the expression $ \frac{3x - 3y}{5x - 5y} $. 2. We start by factoring out the common factors in the numerator and denominator. 3. Factor out 3 from the numerator: $3x - 3y = 3(x - y)$. 4. Factor out 5 from the denominator: $5x - 5y = 5(x - y)$. 5. Substitute back into the fraction: $$\frac{3(x - y)}{5(x - y)}$$ 6. Since $x - y$ is common in numerator and denominator and assuming $x \neq y$, we can cancel it: $$\frac{3\cancel{(x - y)}}{5\cancel{(x - y)}} = \frac{3}{5}$$ 7. Therefore, the simplified form of the expression is $\frac{3}{5}$.