б) (1/12 + 1/13)² : (1/12 - 1/13)² · (1/10)³.

б)

$$ \left(\frac{1}{12} + \frac{1}{13}\right)^2 : \left(\frac{1}{12} - \frac{1}{13}\right)^2 \cdot \left(\frac{1}{10}\right)^3 = \left(\frac{13}{12 \cdot 13} + \frac{12}{13 \cdot 12}\right)^2 : \left(\frac{13}{12 \cdot 13} - \frac{12}{13 \cdot 12}\right)^2 \cdot \left(\frac{1}{10}\right)^3 = \left(\frac{13 + 12}{156}\right)^2 : \left(\frac{13 - 12}{156}\right)^2 \cdot \frac{1}{1000} = \left(\frac{25}{156}\right)^2 : \left(\frac{1}{156}\right)^2 \cdot \frac{1}{1000} = \frac{25^2}{156^2} : \frac{1^2}{156^2} \cdot \frac{1}{1000} = \frac{25^2}{156^2} \cdot \frac{156^2}{1} \cdot \frac{1}{1000} = \frac{25^2}{1} \cdot \frac{1}{1000} = \frac{625}{1000} = \frac{5 \cdot 125}{8 \cdot 125} = \frac{5}{8} $$.

Ответ: 5/8