\[\frac{y + 3}{4y(y - 3)} - \frac{y - 3}{4y(y + 3)} =\]
\[= \frac{(y + 3)^{2} - (y - 3)^{2}}{4y(y - 3)(y + 3)} =\]
\[= \frac{6 \cdot 2y}{4y(y^{2} - 9)} = \frac{3}{y² - 9}\]