Решение:
$$\begin{aligned} \frac{2.5^2 - 2.3^2}{5.7^2 - 2 \cdot 5.7 \cdot 5.9 + 5.9^2} &= \frac{(2.5 - 2.3)(2.5 + 2.3)}{(5.7 - 5.9)^2} \\ &= \frac{0.2 \cdot 4.8}{(-0.2)^2} \\ &= \frac{0.2 \cdot 4.8}{0.04} \\ &= \frac{4.8}{0.2} \\ &= 24 \end{aligned}$$Ответ: 24