Ответ:

  1. а) \(7\frac{11}{12}:3\frac{1}{6}=\frac{95}{12}:\frac{19}{6}=\frac{95}{12}\cdot\frac{6}{19}=\frac{5}{2}=2\frac{1}{2}\).
  2. б) \(3\frac{2}{5}:2\frac{4}{15}=\frac{17}{5}:\frac{34}{15}=\frac{17}{5}\cdot\frac{15}{34}=\frac{3}{2}=1\frac{1}{2}\).
  3. в) \(3{,}4:20{,}4=\frac{34}{10}:\frac{204}{10}=\frac{34}{204}=\frac{1}{6}\).
  4. г) \(1{,}71:1\frac{4}{5}=\frac{171}{100}:\frac{9}{5}=\frac{171}{100}\cdot\frac{5}{9}=\frac{19}{20}=0{,}95\).

Ответ: а) 2 1/2; б) 1 1/2; в) 1/6; г) 0,95.