Вычислить:
$$2. \frac{172\frac{5}{6} - 170\frac{1}{3} + 3\frac{5}{12}}{0,8 \cdot 0,25} = 29\frac{7}{12}.$$

Решение.
\(
2. \frac{172\frac{5}{6} - 170\frac{1}{3} + 3\frac{5}{12}}{0,8 \cdot 0,25} = 29\frac{7}{12}.
\)

\(
1) 172\frac{5}{6} - 170\frac{1}{3} = 172\frac{5}{6} - 170\frac{2}{6} = 2\frac{3}{6} = 2\frac{1}{2};
\)

\(
2) 2\frac{1}{2} + 3\frac{5}{12} = 2\frac{6}{12} + 3\frac{5}{12} = 5\frac{11}{12};
\)

\(
3) 0,8 \cdot 0,25 = \frac{8}{10} \cdot \frac{25}{100} = \frac{4}{5} \cdot \frac{1}{4} = \frac{4 \cdot 1}{5 \cdot 4} = \frac{1 \cdot 1}{5 \cdot 1} = \frac{1}{5};
\)

\(
4) 5\frac{11}{12} : \frac{1}{5} = \frac{71}{12} \cdot \frac{5}{1} = \frac{71\cdot 5}{12\cdot 1} = \frac{355}{12} = 29\frac{7}{12}.
\)
Ответ: \(29\frac{7}{12}\).