Question

a man age is three times that of his son and twelve years he will be twice as old as his son would be.what are their present age?

Answer 1

Let the son age be x and father's age be y.
y=3x

12 years later,
y+12=2(x+12)
Substituting for y,
3x+12=2x+24
3x-2x=24-12
x=12
Father's age=3(12)=36

The son is 12 years old and his father is 36 years old at present.   

Answer 2

let their present ages be x and 3x
after twelve years their ages will be x+12 and 3x+12
a/q 2(x+12)=3x+12
2x+24=3x+12
therefore x is 12
so we finally got the present age of son which is 12 years and man's age is 36 years ...