2. Сложение и вычитание смешанных чисел.

1) \(6\frac{5}{12}-3\frac{3}{8}=\frac{77}{12}-\frac{27}{8}=\frac{154-81}{24}=\frac{73}{24}=3\frac{1}{24}\).

2) \(5\frac{6}{7}-3\frac{1}{14}=\frac{83}{14}-\frac{43}{14}=\frac{40}{14}=2\frac{6}{7}\).

3) \(6\frac{5}{7}-2=4\frac{5}{7}\).

4) \(2\frac{11}{20}+4\frac{19}{30}=6+\frac{33}{60}+\frac{38}{60}=6\frac{71}{60}=7\frac{11}{60}\).

5) \(2\frac{3}{10}-1\frac{7}{15}=\frac{23}{10}-\frac{22}{15}=\frac{69-44}{30}=\frac{25}{30}=\frac{5}{6}\).

6) \(6\frac{5}{12}-3\frac{1}{4}=\frac{77}{12}-\frac{39}{12}=\frac{38}{12}=3\frac{1}{6}\).

7) \(3-3\frac{18}{19}=-\frac{18}{19}\).

8) \(10-3\frac{3}{8}=6\frac{5}{8}\).

9) \(6\frac{11}{15}-8\frac{3}{5}=\frac{101}{15}-\frac{129}{15}=-\frac{28}{15}=-1\frac{13}{15}\).

Ответ: 1) 3 1/24; 2) 2 6/7; 3) 4 5/7; 4) 7 11/60; 5) 5/6; 6) 3 1/6; 7) −18/19; 8) 6 5/8; 9) −1 13/15.