After 12 years, Kanwar shall be 3 times

Let Kanwar's present age be $x$ yr.

After 12.yr, Kanwar's age $=(x+12)$ y

and 4 yr ago, Kanwar's age $=(x-4)$ yr

According to the question,

$x+12=3(x-4) \Rightarrow x+12=3 x-12$

$\Rightarrow \quad 3 x-x=12+12 \Rightarrow 2 x=24$

$\Rightarrow$ $x=\frac{24}{2}$

$\therefore \quad x=12$

Hence, Kanwar's present age is $12 \mathrm{yr}$.