а) Решим уравнение:
$$\frac{17}{71} + x = \frac{41}{71}$$ $$x = \frac{41}{71} - \frac{17}{71}$$ $$x = \frac{41 - 17}{71}$$ $$x = \frac{24}{71}$$
б) Решим уравнение:
$$\frac{28}{35} - y = \frac{13}{35}$$ $$y = \frac{28}{35} - \frac{13}{35}$$ $$y = \frac{28 - 13}{35}$$ $$y = \frac{15}{35}$$ $$y = \frac{3}{7}$$
Ответ: a) $$x = \frac{24}{71}$$; б) $$y = \frac{3}{7}$$