DRDO Multi tasking staff Model paper 1

Now when the man is 50 years old and his brother is 7 years older than him
∴ the age of brother will be 57 years
Now as the sister is 12 years younger than his brother
∴ the age of sister will be (57 – 12) = 45 years
So the present age of man, brother and sister is 50, 57 and 45 respectively
∴ When his sister was 20 years old i.e. (45 - 20) 25 years ago the men’s age will be (50 – 25) = 25 years