Решим уравнение:
$$y : 8 = 2\frac{11}{20}$$
$$y : 8 = \frac{2 \cdot 20 + 11}{20}$$
$$y : 8 = \frac{40 + 11}{20}$$
$$y : 8 = \frac{51}{20}$$
$$y = \frac{51}{20} \cdot 8$$
$$y = \frac{51 \cdot 8}{20}$$
$$y = \frac{51 \cdot 2}{5}$$
$$y = \frac{102}{5}$$
$$y = 20,4$$
Ответ: 20,4