\(\frac{x}{4}=\frac{y}{6}=\frac{z}{-3}\)
=> \(\frac{x^3}{4^3}=\frac{y^3}{6^3}=\frac{z^3}{\left(-3\right)^3}=\frac{x.y.z}{4.6.\left(-3\right)}=\frac{576}{-72}=-8\)
=> \(\frac{x^3}{4^3}=-8\) => x3 = -512 => x = -8
\(\frac{y^3}{6^3}=-8\) => x3 = -1728 => x = -12
\(\frac{z^3}{\left(-3\right)^3}=-8\) => z3 = 216 => x = 6