Ответ:

Блок 1: \(\frac{1}{5}-\frac{41}{50}=\frac{10}{50}-\frac{41}{50}=-\frac{31}{50}\).

Блок 2: \(\frac{21}{5}:\frac{6}{7}=\frac{21}{5}\cdot\frac{7}{6}=\frac{49}{10}\).

Блок 3: \(\left(\frac{17}{15}-\frac{1}{12}\right)\cdot\frac{20}{3}=\left(\frac{68}{60}-\frac{5}{60}\right)\cdot\frac{20}{3}=\frac{21}{20}\cdot\frac{20}{3}=7\).

Ответ: Блок 1 — \(-\frac{31}{50}\); Блок 2 — \(\frac{49}{10}\); Блок 3 — \(7\).