1. Найдите значение выражения: 1) 1/2 + 11/10; 2) 1/10 − 39/50; 3) 7/6 · 9/5; 4) 21/2 · 3/5.

1. \(\frac{1}{2}+\frac{11}{10}=\frac{5}{10}+\frac{11}{10}=\frac{16}{10}=\frac{8}{5}\).
2. \(\frac{1}{10}-\frac{39}{50}=\frac{5}{50}-\frac{39}{50}=\frac{-34}{50}=-\frac{17}{25}\).
3. \(\frac{7}{6}\cdot\frac{9}{5}=\frac{63}{30}=\frac{21}{10}\).
4. \(\frac{21}{2}\cdot\frac{3}{5}=\frac{63}{10}\).

Ответ: 1) \(\frac{8}{5}\); 2) \(-\frac{17}{25}\); 3) \(\frac{21}{10}\); 4) \(\frac{63}{10}\).