Given that,
We can combine the ratios,
- $a:b=(3:4)\times 2 = 6:8$
- $b:c=(2:1)\times 4 = 8:4$
$\Rightarrow a:b:c =6:8:4=3:4:2$
Let $a=3k,b=4k,c=2k$
$\therefore$ The value of $a+b+c = 3k+4k+2k= 9k$
The number $207$ is divisible by $9$. We can write $207 = 9 \cdot 23.$
$\textbf{PS:}\; \textsf{Divisibility by 9:-}$ The sum of digits of the number must be divisible by $9.$
Correct Answer $:\text{C}$