Ответ:
- \[\frac{5}{8}+\frac{3}{4}-\frac{1}{2}=\frac{5}{8}+\frac{6}{8}-\frac{4}{8}=\frac{7}{8}.\]
- \[\frac{7}{9}-\frac{2}{3}+\frac{1}{6}=\frac{14}{18}-\frac{12}{18}+\frac{3}{18}=\frac{5}{18}.\]
- \[\frac{4}{15}\cdot\frac{5}{8}=\frac{20}{120}=\frac{1}{6}.\]
- \[\frac{9}{10}:\frac{3}{5}=\frac{9}{10}\cdot\frac{5}{3}=\frac{3}{2}=1\frac{1}{2}.\]
