1. Решим уравнение:
$$a:1\frac{5}{7}=2\frac{2}{5}:2\frac{2}{35}$$
$$a:\frac{12}{7}=\frac{12}{5}:\frac{72}{35}$$
$$a:\frac{12}{7}=\frac{12}{5} \cdot \frac{35}{72}$$
$$a:\frac{12}{7}=\frac{12 \cdot 35}{5 \cdot 72}$$
$$a:\frac{12}{7}=\frac{1 \cdot 7}{1 \cdot 6}$$
$$a:\frac{12}{7}=\frac{7}{6}$$
$$a = \frac{7}{6} \cdot \frac{12}{7}$$
$$a = \frac{1 \cdot 2}{1 \cdot 1}$$
$$a = 2$$
Ответ: a = 2