Questions asked
(c) \( \left[\frac{a^{0} b^{-1} a^{-2} b a^{-3}}{a b^{-1}}\right]^{-2} \)
(a) \( \frac{1}{3} x^{9}-\frac{2}{7} x^{4}+\frac{17}{19} x \)
\( \frac{7}{8} x y, \frac{9}{4} x y z,-\frac{15}{11} \mathrm{txz} \)
