6 +31.3 7.1 11711

$$7\frac{6}{7} \cdot 1\frac{6}{11} + 3\frac{1}{7} \cdot \frac{3}{11} = \frac{7 \cdot 7 + 6}{7} \cdot \frac{1 \cdot 11 + 6}{11} + \frac{3 \cdot 7 + 1}{7} \cdot \frac{3}{11} = \frac{49 + 6}{7} \cdot \frac{11 + 6}{11} + \frac{21 + 1}{7} \cdot \frac{3}{11} = \frac{55}{7} \cdot \frac{17}{11} + \frac{22}{7} \cdot \frac{3}{11} = \frac{5 \cdot 11 \cdot 17}{7 \cdot 11} + \frac{2 \cdot 11 \cdot 3}{7 \cdot 11} = \frac{5 \cdot 17}{7} + \frac{2 \cdot 3}{7} = \frac{85}{7} + \frac{6}{7} = \frac{85 + 6}{7} = \frac{91}{7} = 13$$

Ответ: 13