a) 1$$\frac{4}{15} - \frac{17}{20};$$ б) 7$$\frac{4}{15} - \frac{7}{9};$$ в) 2$$\frac{5}{12} - \frac{7}{8};$$ г) 11$$\frac{1}{2} - 3\frac{11}{18};$$ д) 9$$\frac{2}{11} - 7\frac{5}{9};$$ e) 2$$\frac{6}{25} - 1\frac{7}{10};$$ ж) 3$$\frac{1}{2} - 2\frac{3}{4};$$ з) 12$$\frac{5}{12} - 9\frac{13}{18}.$$

Решим данные примеры:

1. a) $$1\frac{4}{15} - \frac{17}{20} = \frac{19}{15} - \frac{17}{20} = \frac{19 \cdot 4}{15 \cdot 4} - \frac{17 \cdot 3}{20 \cdot 3} = \frac{76}{60} - \frac{51}{60} = \frac{76 - 51}{60} = \frac{25}{60} = \frac{5}{12}$$
2. б) $$7\frac{4}{15} - \frac{7}{9} = \frac{109}{15} - \frac{7}{9} = \frac{109 \cdot 3}{15 \cdot 3} - \frac{7 \cdot 5}{9 \cdot 5} = \frac{327}{45} - \frac{35}{45} = \frac{327 - 35}{45} = \frac{292}{45} = 6\frac{22}{45}$$
3. в) $$2\frac{5}{12} - \frac{7}{8} = \frac{29}{12} - \frac{7}{8} = \frac{29 \cdot 2}{12 \cdot 2} - \frac{7 \cdot 3}{8 \cdot 3} = \frac{58}{24} - \frac{21}{24} = \frac{58 - 21}{24} = \frac{37}{24} = 1\frac{13}{24}$$
4. г) $$11\frac{1}{2} - 3\frac{11}{18} = \frac{23}{2} - \frac{65}{18} = \frac{23 \cdot 9}{2 \cdot 9} - \frac{65}{18} = \frac{207}{18} - \frac{65}{18} = \frac{207 - 65}{18} = \frac{142}{18} = \frac{71}{9} = 7\frac{8}{9}$$
5. д) $$9\frac{2}{11} - 7\frac{5}{9} = \frac{101}{11} - \frac{68}{9} = \frac{101 \cdot 9}{11 \cdot 9} - \frac{68 \cdot 11}{9 \cdot 11} = \frac{909}{99} - \frac{748}{99} = \frac{909 - 748}{99} = \frac{161}{99} = 1\frac{62}{99}$$
6. e) $$2\frac{6}{25} - 1\frac{7}{10} = \frac{56}{25} - \frac{17}{10} = \frac{56 \cdot 2}{25 \cdot 2} - \frac{17 \cdot 5}{10 \cdot 5} = \frac{112}{50} - \frac{85}{50} = \frac{112 - 85}{50} = \frac{27}{50}$$
7. ж) $$3\frac{1}{2} - 2\frac{3}{4} = \frac{7}{2} - \frac{11}{4} = \frac{7 \cdot 2}{2 \cdot 2} - \frac{11}{4} = \frac{14}{4} - \frac{11}{4} = \frac{14 - 11}{4} = \frac{3}{4}$$
8. з) $$12\frac{5}{12} - 9\frac{13}{18} = \frac{149}{12} - \frac{175}{18} = \frac{149 \cdot 3}{12 \cdot 3} - \frac{175 \cdot 2}{18 \cdot 2} = \frac{447}{36} - \frac{350}{36} = \frac{447 - 350}{36} = \frac{97}{36} = 2\frac{25}{36}$$

Ответ: a) $$\frac{5}{12}$$; б) $$6\frac{22}{45}$$; в) $$1\frac{13}{24}$$; г) $$7\frac{8}{9}$$; д) $$1\frac{62}{99}$$; e) $$\frac{27}{50}$$; ж) $$\frac{3}{4}$$; з) $$2\frac{25}{36}$$