(i) We have,

x = \(\frac{-7}{3}\), y = \(\frac{12}{5}\) and z = \(\frac{4}{9}\)

= x x (y x z) = \(\frac{-7}{3}\times (\frac{12}{5}\times \frac{4}{9})\)

= \(\frac{-7}{3}(\frac{48}{45})\)

= \(\frac{-112}{45}\)

(x x y) x z = \((\frac{-7}{3}\times \frac{12}{5})\times \frac{4}{9}\)

= \(\frac{-7}{3}(\frac{48}{45})\)

= \(\frac{-112}{45}\)

(ii) We have,

 x = 0, y = \(\frac{-3}{5}\) and z = \(\frac{-9}{4}\)

= x x (y x z) = \(0\times (\frac{-3}{5}\times \frac{-9}{4})\)

 = 0

 (x x y) x z = \((0\times \frac{-3}{5})\times \frac{-9}{4}\)

 = 0

(iii) We have,

 x = \(\frac{1}{2}\), y = \(\frac{5}{-4}\) and z = \(\frac{-7}{5}\)

= x x (y x z) = \(\frac{1}{2}\times (\frac{5}{-4}\times \frac{-7}{5})\)

= \(\frac{1}{2}(\frac{7}{4})\)

= \(\frac{7}{8}\)

 (x x y) x z = \((\frac{1}{2}\times \frac{5}{-4})\times \frac{-7}{5}\)

= \(\frac{-5}{8}(\frac{-7}{5})\)

= \(\frac{7}{8}\)

(iv) We have,

  x = \(\frac{5}{7}\), y = \(\frac{-12}{13}\) and z = \(\frac{-7}{18}\)

= x x (y x z) = \(\frac{5}{7}\times (\frac{-12}{13}\times \frac{-7}{18})\)

 = \(\frac{10}{39}\)

  (x x y) x z = \((\frac{5}{7}\times \frac{-12}{13})\times \frac{-7}{8}\)

= \(\frac{60}{91}(\frac{-7}{18})\)

= \(\frac{10}{39}\)