If x : 12 :: 4 : 6 then x value is

Correct option is B

Given
Proportion: x : 12 :: 4 : 6

Formula Used
Product of extremes = Product of means
​$$a : b :: c : d \Rightarrow a × d = b × c$$​​
Solution
According to the rule of proportion:
​$$x × 6 = 12 × 4\\6x = 48\\x = \frac{48}{6}\\x = 8$$​​
So the correct answer is (b)