22. Найдите сумму или разность.

Решение:

1. \( \frac{21}{66} + \frac{22}{66} = \frac{21+22}{66} = \frac{43}{66} \)

2. \( \frac{21}{20} - \frac{1}{20} = \frac{21-1}{20} = \frac{20}{20} = 1 \)

3. \( \frac{55}{9} - \frac{12}{9} = \frac{55-12}{9} = \frac{43}{9} = 4 \frac{7}{9} \)

4. \( \frac{66}{20} - \frac{43}{20} = \frac{66-43}{20} = \frac{23}{20} = 1 \frac{3}{20} \)

Ответ: 1. \(\frac{43}{66}\); 2. 1; 3. 4 \(\frac{7}{9}\); 4. 1 \(\frac{3}{20}\).