3) 4 2/7 - 1 4/9 5) 9 7/9 - 4 5/6

Решение:

1. 3) 4 2/7 - 1 4/9
   \[ 4 \frac{2}{7} - 1 \frac{4}{9} = (4-1) + (\frac{2}{7} - \frac{4}{9}) = 3 + \frac{18-28}{63} = 3 - \frac{10}{63} = 2 + \frac{63}{63} - \frac{10}{63} = 2 \frac{53}{63} \]
2. 5) 9 7/9 - 4 5/6
   \[ 9 \frac{7}{9} - 4 \frac{5}{6} = (9-4) + (\frac{7}{9} - \frac{5}{6}) = 5 + \frac{14-15}{18} = 5 - \frac{1}{18} = 4 + \frac{18}{18} - \frac{1}{18} = 4 \frac{17}{18} \]

Ответ: 3) 2 53/63; 5) 4 17/18