Question

Father's ages is three times hos son's age. Four years ago, he was $4$ times his son's age. Find their present ages.

Answer 1

Let present age of the son is $x$ years.

Then the age of the father is $3x$ years.

Then according to the problem we get,

$3x-4=4\left(x-4\right)$

or, $4x-3x=16-4$

$x=12$.

So the son's age is $12$ years and that of the father is $12\times 3=36$ years.