Tìm x thoả mãn
a) \(-\frac{8}{3}+\frac{7}{5}+\frac{-71}{15}\)< x < \(-\frac{13}{7}+\frac{19}{14}+\frac{-7}{2}\)
b) \(\frac{5}{17}+\frac{-4}{9}+\frac{-20}{31}+\frac{12}{17}+\frac{-11}{31}\) < \(\frac{x}{9}\) < \(\frac{-3}{7}+\frac{7}{15}+\frac{4}{-7}+\frac{8}{15}+\frac{2}{3}\)