Найдем разность:

1. a) $$13\frac{8}{9} - 4 = (13 - 4) + \frac{8}{9} = 9 + \frac{8}{9} = 9\frac{8}{9}$$
2. б) $$17\frac{5}{14} - 5\frac{3}{14} = (17 - 5) + (\frac{5}{14} - \frac{3}{14}) = 12 + \frac{2}{14} = 12\frac{1}{7}$$
3. в) $$9\frac{5}{7} - 3\frac{6}{7} = 9\frac{5}{7} - 3\frac{6}{7} = 8 + \frac{7}{7} + \frac{5}{7} - 3\frac{6}{7} = 8\frac{12}{7} - 3\frac{6}{7} = (8 - 3) + (\frac{12}{7} - \frac{6}{7}) = 5 + \frac{6}{7} = 5\frac{6}{7}$$
4. г) $$100 - 20\frac{3}{14} = 100 - 20 - \frac{3}{14} = 80 - \frac{3}{14} = 79 + \frac{14}{14} - \frac{3}{14} = 79\frac{11}{14}$$

Ответ:

• a) $$9\frac{8}{9}$$
• б) $$12\frac{1}{7}$$
• в) $$5\frac{6}{7}$$
• г) $$79\frac{11}{14}$$