ANSWER
In 4 years time.
EXPLANATION
The present age of the child is 12 years.
The present age of the father is (12+32)=44 years.
In x years time,
The child's age will be
[tex](12 + x) \: years[/tex]
The father's age will be,
[tex](44 + x) \: years[/tex]
If in x years time, the father's age is three times the son's age, then we can write the following equation and solve for x.
[tex](44 + x) = 3(12 + x)[/tex]
Expand the bracket,
[tex]44 + x = 36 + 3x[/tex]
Group similar terms,
[tex]44 - 36 = 3x - x[/tex]
This implies that,
[tex]8 = 2x[/tex]
Dividing through by 2 gives,
[tex]x = 4[/tex]
