Ответ:
Приведём дроби к общему знаменателю и выполним действия.
\(25\frac{5}{11}+3\frac{6}{7}=28+\frac{5}{11}+\frac{6}{7}=28+\frac{35}{77}+\frac{66}{77}=28\frac{101}{77}=29\frac{24}{77}\).
\(14\frac{7}{9}-1\frac{1}{6}=13+\frac{7}{9}-\frac{1}{6}=13+\frac{14}{18}-\frac{3}{18}=13\frac{11}{18}\).
\(2\frac{9}{20}-\left(\frac{1}{4}+1\frac{1}{5}\right)=2\frac{9}{20}-\left(\frac{5}{20}+1\frac{4}{20}\right)=2\frac{9}{20}-1\frac{9}{20}=1\).
\(\frac{5}{6}+\left(6\frac{5}{9}-\frac{1}{4}\right)=\frac{5}{6}+\left(6+\frac{20}{36}-\frac{9}{36}\right)=\frac{5}{6}+6\frac{11}{36}=6+\frac{30}{36}+\frac{11}{36}=6\frac{41}{36}=7\frac{5}{36}\).
Ответ: 1) \(29\frac{24}{77}\); 2) \(13\frac{11}{18}\); 3) \(1\); 4) \(7\frac{5}{36}\).
