My father is 21 years older than me. In 12 years time, his age will be twice mine. How old am I now?

Suppose my age = P years My father’s age = my age + 21 years = P + 21 years Again After 12 years , 2 ( my age + 12 ) = My father’s age + 12 ⇒ 2 (P + 12) = (P + 21) + 12 ⇒ 2P + 24 = P + 33 ⇒ P = 33 – 24 = 9 years Hence , I am 9 years old now .