Question

the presant age of father is three years more thrice the age of his son.three years hence the fater will be 10 years more than twice his son. after how many years fathers age will be double the age of the son?

Answer 1

Let the son's present age be y years
Father 's present age is 3y +3
After 3 years son's age will be y + 3 years
After 3 years father' s age will be 3y + 6 years
As per condition,
$3y + 6 = 2(y + 3) + 10 \\ y = 10$
Now let his fathers age will be double the age of the son after x years after 3 years from the present
$36 + x = 2(13 + x) \\ x = 10$