3. 3) (8-60:10:40: 66 36

3) $$\left(8\frac{5}{7}-6\frac{5}{6}:1\frac{5}{36}\right):4\frac{3}{4}=\left(\frac{61}{7}-\frac{41}{6}:\frac{41}{36}\right):\frac{19}{4}=\left(\frac{61}{7}-\frac{41}{6} \cdot \frac{36}{41}\right):\frac{19}{4}=\left(\frac{61}{7}-6\right):\frac{19}{4}=\left(\frac{61}{7}-\frac{42}{7}\right):\frac{19}{4}=\frac{19}{7}:\frac{19}{4}=\frac{19}{7} \cdot \frac{4}{19}=\frac{4}{7}$$

Ответ: $$\frac{4}{7}$$