Answer:
Let current age of father be x and current age of his son be y.
So 3 years ago, difference between their age was 24.
Therefore equation becomes
(x-3)-(y-3) = 24.
x - y = 24.
At present father is 5 times as old as son.
x = 5y.
Therefore 5y - y = 24.
y = 6.
Current age of son is 6 years. So after three years he will be 9 years old.
Explanation: