\[9y^{2} - 25 = 0\]
\[9y^{2} = 25\]
\[y^{2} = \frac{25}{9}\]
\[y = \pm \frac{5}{3} = \pm 1\frac{2}{3}\]
\[Ответ:y = \pm 1\frac{2}{3}.\]