Ответ:

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

Ответ: Блок 1 — \(\frac{41}{20}\); Блок 2 — \(\frac{14}{5}\); Блок 3 — \(\frac{22}{5}\).