After 12 years, I shall be 3 times as old as I was 4 years ago. Find my present age.

Let my present age be x years.

According to question, after 12 years, I shall be 3 times as old as I was 4 years ago.

⇒ (present age + 12 years) = 3(present age - 4 years)

⇒ (x + 12) = 3(x - 4)

⇒ x + 12 = 3x - 12

⇒ 3x - x = 12 + 12

⇒ 2x = 24

⇒ x = $\dfrac{24}{2}$

⇒ x = 12

Hence, my present age is 12 years.