A : B : C = 2 : 3 : 4
A/B : B/C : C/A
Let A = 2x , B = 3x and C = 4x
Then,
$\frac{A}{B} = \frac{2x}{3x} = \frac{2}{3}$
$\frac{B}{C} = \frac{3x}{4x} = \frac{3}{4}$
$\frac{C}{A} = \frac{4x}{2x} = \frac{2}{1}$
$\begin{align*}\text{A/B : B/C : C/A} & = 2/3 : 3/4 : 2/1 \\ &=8: 9 : 24\end{align*}$