Tìm x

B1:
a)$\frac{x-1}{2}=\frac{y-2}{3}=\frac{z-3}{4} vs x-2y+3z=14$
b)$$\begin{gathered} \frac{a}{3b}=\frac{b}{3c}=\frac{c}{3d}=\frac{d}{3a} vs a+b+c+d khac 0 \\ CMR:a=b=c=d \end{gathered}$$​