Question

A father is 42 years old and his son is 12 years old in how many years will the age of the son be half the age of the father at that time

Answer 1

after 18 years i.e. father=42+18=60
son=12+18=30
the half of 60 is 30.

Answer 2

Let in x years,

(42+x)/2 =(12+x)


42+x =24+2x

42-24 =2x-x

18 =x



Now,

After 18 years, son's age will be half of fatger's age

I hope this will help you


-by ABHAY