1) а) 1/3 + 5/6; б) 5/7 − 1/14; в) 2 2/3 + 5 5/12; 2) а) 8/11 − 1/13; б) 7/20 + 2/3; в) 3 2/15 − 1 1/7; 3) а) 5/34 − 11/51; б) 3 1/30 − 5 7/90; в) 6 1/7 − 10 3/14.

1)

1. а) Приведём к общему знаменателю 6: \(\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{7}{6}=1\frac{1}{6}\).
2. б) \(\frac{5}{7}-\frac{1}{14}=\frac{10}{14}-\frac{1}{14}=\frac{9}{14}\).
3. в) \(2\frac{2}{3}+5\frac{5}{12}=7+\frac{8}{12}+\frac{5}{12}=7+\frac{13}{12}=8\frac{1}{12}\).

2)

1. а) \(\frac{8}{11}-\frac{1}{13}=\frac{104}{143}-\frac{11}{143}=\frac{93}{143}\).
2. б) \(\frac{7}{20}+\frac{2}{3}=\frac{21}{60}+\frac{40}{60}=\frac{61}{60}=1\frac{1}{60}\).
3. в) \(3\frac{2}{15}-1\frac{1}{7}=2+\frac{2}{15}-\frac{1}{7}=2+\frac{14-3}{105}=2\frac{11}{105}\).

3)

1. а) \(\frac{5}{34}-\frac{11}{51}=\frac{15}{102}-\frac{22}{102}=-\frac{7}{102}\).
2. б) \(3\frac{1}{30}-5\frac{7}{90}=3\frac{3}{90}-5\frac{7}{90}=-2-\frac{4}{90}=-2\frac{2}{45}\).
3. в) \(6\frac{1}{7}-10\frac{3}{14}=6\frac{2}{14}-10\frac{3}{14}=-4-\frac{1}{14}=-4\frac{1}{14}\).

Ответ: 1) а) \(1\frac{1}{6}\); б) \(\frac{9}{14}\); в) \(8\frac{1}{12}\). 2) а) \(\frac{93}{143}\); б) \(1\frac{1}{60}\); в) \(2\frac{11}{105}\). 3) а) \(-\frac{7}{102}\); б) \(-2\frac{2}{45}\); в) \(-4\frac{1}{14}\).