Ответ:

\(\frac{5}{6}-0,7=\frac{5}{6}-\frac{7}{10}=\frac{2}{15}\).

\(1,8\cdot\frac{2}{15}=\frac{9}{5}\cdot\frac{2}{15}=\frac{6}{25}\).

\(1\frac{4}{5}:7,5=\frac{9}{5}:\frac{15}{2}=\frac{9}{5}\cdot\frac{2}{15}=\frac{6}{25}\).

Следовательно, \(\frac{6}{25}-\frac{6}{25}=0\).

Ответ: 0.