22.61; 78

$$ \left( \frac{2}{7} \right)^2 \cdot 6 \frac{1}{8} = \frac{2^2}{7^2} \cdot \frac{6 \cdot 8 + 1}{8} = \frac{4}{49} \cdot \frac{48+1}{8} = \frac{4}{49} \cdot \frac{49}{8} = \frac{4 \cdot 49}{49 \cdot 8} = \frac{4}{8} = \frac{1}{2} $$

Ответ: 1/2