#### Answer

$-\frac{2}{9}$

#### Work Step by Step

When $x=-\frac{1}{3}$, y=$\frac{2}{5}$,and $z=\frac{5}{6}$
$x^{2}-yz$
$=(-\frac{1}{3})^{2}-(\frac{2}{5}\times\frac{5}{6})$
$=[(-\frac{1}{3})\times(-\frac{1}{3})]-(\frac{1}{1}\times\frac{1}{3})$
$=(\frac{1}{3}\times\frac{1}{3})-\frac{1}{3}$
$=\frac{1}{9}-\frac{1}{3}$
$=\frac{1}{9}-\frac{3}{9}$
$=-\frac{2}{9}$