\[\frac{16x - 25y}{4\sqrt{x} - 5\sqrt{y}} - \sqrt{y} =\]
\[= \frac{\left( 4\sqrt{x} - 5\sqrt{y} \right)\left( 4\sqrt{x} + 5\sqrt{y} \right)}{4\sqrt{x} - 5\sqrt{y}} - \sqrt{y} =\]
\[= 4\sqrt{x} + 5\sqrt{y} - \sqrt{y} =\]
\[= 4\sqrt{x} + 4\sqrt{y} = 4\left( \sqrt{x} + \sqrt{y} \right);\]
\[\sqrt{x} + \sqrt{y} = 3:\]
\[4 \cdot 3 = 12.\]