5. Блок 1: 1/2 + 31/20; Блок 2: 4/5 : 2/7; Блок 3: (1/5 + 8/15) · 6. Вычислите.

Блок 1. \(\frac{1}{2}+\frac{31}{20}=\frac{10}{20}+\frac{31}{20}=\frac{41}{20}\).

Блок 2. \(\frac{4}{5}:\frac{2}{7}=\frac{4}{5}\cdot\frac{7}{2}=\frac{14}{5}\).

Блок 3. \(\left(\frac{1}{5}+\frac{8}{15}\right)\cdot6=\left(\frac{3}{15}+\frac{8}{15}\right)\cdot6=\frac{11}{15}\cdot6=\frac{22}{5}\).