a) 25 34 - 4 17; б) 17 18 - 7 54; в) 11 19 - 43 76; г) 49 75 - 8 25.

а)
\( \frac{25}{34} - \frac{4}{17} = \frac{25}{34} - \frac{8}{34} = \frac{17}{34} = \frac{1}{2} \)

б)
\( \frac{17}{18} - \frac{7}{54} = \frac{51}{54} - \frac{7}{54} = \frac{44}{54} = \frac{22}{27} \)

в)
\( \frac{11}{19} - \frac{43}{76} = \frac{44}{76} - \frac{43}{76} = \frac{1}{76} \)

г)
\( \frac{49}{75} - \frac{8}{25} = \frac{49}{75} - \frac{24}{75} = \frac{25}{75} = \frac{1}{3} \)