\[\frac{3a^{3} - 48a}{5a^{3} - 40a^{2} + 80a};\ \ \]
\[если\ \ a = 16.\]
\[\frac{3a^{3} - 48a}{5a^{3} - 40a^{2} + 80a} =\]
\[= \frac{3 \cdot (a + 4)}{5 \cdot (a - 4)} = \frac{3 \cdot (16 + 4)}{5 \cdot (16 - 4)} =\]
\[= \frac{3 \cdot 20}{5 \cdot 12} = \frac{60}{60} = 1.\]