б) (\frac{1}{12} + \frac{1}{13})^2 : (\frac{1}{12} - \frac{1}{13})^2 \cdot (\frac{1}{10})^3.

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

Ответ: $$\frac{5}{8}$$