Aman is five times as old as his son. four years ago, he was nine times as old. find their present ages.

Let us assume the age of the son now = x
Then
The age of the man now = 5x
Now we have to calculate the age of the son and father 9 years ago
Age of the son 4 years ago = x - 4
Age of the man 4 years ago = 5x - 4
Then
5x - 4 = 9(x - 4)
5x - 4 = 9x - 36
5x - 9x = -36 + 4
- 4x = - 32
MUltiplying both sides of the equation by -1 we get
4x = 32
x = 32/4
  = 8
So the present age of the son is 8 years
Present age of the man = 5x
                                       = 5 * 8
                                       = 40 years
So the present age of the man is 40 years and the present age of the son is 8 years.