$$\left. \begin{array} { l } { x \times ( y \times z ) = ( x \times y ) \times z } \\ { x = \frac { - 1 } { 2 } , y = \frac { 2 } { 3 } , z = \frac { 3 } { 4 } } \end{array} \right.$$
$x=-\frac{1}{2}=-0.5$
$y=\frac{2}{3}\approx 0.666666667$
$z=\frac{3}{4}=0.75$
