Ответ:

1) \(\frac{5}{18}+\frac{4}{18}=\frac{9}{18}=\frac12\).

2) \(\frac{25}{34}-\frac{8}{34}=\frac{17}{34}=\frac12\).

3) \(3\frac{13}{45}+6\frac{17}{45}=9\frac{30}{45}=9\frac23\).

4) \(12\frac{43}{56}-7\frac{22}{56}=5\frac{21}{56}=5\frac38\).

Ответ: 1) \(\frac12\); 2) \(\frac12\); 3) \(9\frac23\); 4) \(5\frac38\).