Пример 5. \(1\frac{3}{4}\cdot0,8:\left(\frac{5}{12}-0,25\right)-2,1\cdot\frac{5}{7}\)

\(1\frac{3}{4}=\frac{7}{4}\), \(0,8=\frac{4}{5}\), \(0,25=\frac{1}{4}\), \(2,1=\frac{21}{10}\).

1. \(1\frac{3}{4}\cdot0,8=\frac{7}{4}\cdot\frac{4}{5}=\frac{7}{5}\).
2. \(\frac{5}{12}-0,25=\frac{5}{12}-\frac{1}{4}=\frac{5}{12}-\frac{3}{12}=\frac{1}{6}\).
3. \(\frac{7}{5}:\frac{1}{6}=\frac{7}{5}\cdot6=\frac{42}{5}=8,4\).
4. \(2,1\cdot\frac{5}{7}=\frac{21}{10}\cdot\frac{5}{7}=\frac{3}{2}=1,5\).
5. \(8,4-1,5=6,9\).

Ответ: \(6,9\).