The difference of the ages of Rohit and Axar is $12\text{years}$. The ratio of their ages is $3:5$. The age of Axar is

Let the structural ages of Rohit and Axar be represented as $3x$ and $5x$ respectively, where $x$ serves as the shared proportional constant.
The difference between their ages is given as $12\text{years}$:

$$5x-3x=12$$

$$2x=12⟹x=6$$

The age of Axar is defined as $5x$:

$$\text{Age of Axar}=5\times 6=30\text{years}$$