(6) \( \frac{3 x^{2} y^{-3} z}{x^{2} y^{5} z^{4}}= \)

To simplify the expression \( \frac{3 x^{2} y^{-3} z}{x^{2} y^{5} z^{4}} \), we start by dividing the coefficients and applying the laws of exponents. First, the coefficients give us \( 3 \). Next, for \( x \), \( \frac{x^{2}}{x^{2}} = 1 \); thus, there is no \( x \) left. For \( y \), we have \( \frac{y^{-3}}{y^{5}} = y^{-3-5} = y^{-8} \). Lastly, for \( z \), \( \frac{z}{z^{4}} = z^{1-4} = z^{-3} \). Putting it all together, we have: \[ 3y^{-8}z^{-3} = \frac{3}{y^{8}z^{3}}. \] Final result: \[ \frac{3}{y^{8}z^{3}}. \]