8. \( \frac{2 x^{2}-18}{5 x y-15 y}= \)

To simplify the expression \( \frac{2 x^{2}-18}{5 x y-15 y} \), we can factor both the numerator and the denominator. The numerator can be factored as follows: \( 2 x^{2} - 18 = 2(x^{2} - 9) = 2(x - 3)(x + 3) \). For the denominator, we can factor out the common term: \( 5 x y - 15 y = 5 y(x - 3) \). Now, substituting these factored forms into the original expression gives us: \[ \frac{2(x - 3)(x + 3)}{5 y(x - 3)}. \] We can cancel out the common term \( (x - 3) \), assuming \( x \neq 3 \): \[ \frac{2(x + 3)}{5y}. \] Therefore, the simplified expression is: \[ \frac{2(x + 3)}{5y}. \]