а) \( \frac{c}{4} + \frac{a}{9} \)
б) \( \frac{a}{4c} - \frac{a-3c}{4c} \) = \( \frac{a - (a-3c)}{4c} \) = \( \frac{a-a+3c}{4c} \) = \( \frac{3c}{4c} \) = \( \frac{3}{4} \)
в) \( \frac{17b-6}{4b} - \frac{5b+2}{4b} \) = \( \frac{17b-6 - (5b+2)}{4b} \) = \( \frac{17b-6-5b-2}{4b} \) = \( \frac{12b-8}{4b} \) = \( \frac{3b-2}{b} \)
Ответ: а) \( \frac{c}{4} + \frac{a}{9} \), б) \( \frac{3}{4} \), в) \( \frac{3b-2}{b} \)