178. Найдите значение выражения: 1) −2 3/4 + (−3 2/5); 2) 4 2/7 + (−1 4/5); 3) −6 5/6 + 3 5/8; 4) 5 7/9 + (−3 1/12); 5) 1 7/8 + (−2 3/4); 6) −8/9 + 1 5/8.

1. \(-2\frac{3}{4}+(-3\frac{2}{5})=-\left(2\frac{3}{4}+3\frac{2}{5}\right)=-6\frac{3}{20}\).
2. \(4\frac{2}{7}+(-1\frac{4}{5})=\frac{30}{7}-\frac{9}{5}=\frac{150-63}{35}=\frac{87}{35}=2\frac{17}{35}\).
3. \(-6\frac{5}{6}+3\frac{5}{8}=-\frac{41}{6}+\frac{29}{8}=\frac{-164+87}{24}=-\frac{77}{24}=-3\frac{5}{24}\).
4. \(5\frac{7}{9}+(-3\frac{1}{12})=\frac{52}{9}-\frac{37}{12}=\frac{208-111}{36}=\frac{97}{36}=2\frac{25}{36}\).
5. \(1\frac{7}{8}+(-2\frac{3}{4})=\frac{15}{8}-\frac{22}{8}=-\frac{7}{8}\).
6. \(-\frac{8}{9}+1\frac{5}{8}=-\frac{64}{72}+\frac{117}{72}=\frac{53}{72}\).

Ответ: 1) −6 3/20; 2) 2 17/35; 3) −3 5/24; 4) 2 25/36; 5) −7/8; 6) 53/72.