Ta có: \(\frac{x}{3}=\frac{y}{5};\frac{y}{6}=\frac{z}{7}\Rightarrow\frac{x}{18}=\frac{y}{30}=\frac{z}{35}=\frac{4x}{72}=\frac{8y}{240}=\frac{9z}{315}=\frac{-3}{-3}=1\)
\(\Rightarrow\frac{x}{18}=1\Rightarrow x=18;\frac{y}{30}=1\Rightarrow y=30;\frac{z}{35}=1\Rightarrow z=35\)