Question

five years ago the age of the father was twice the age of his son. the sum of their present ages is 55. find their present ages

Answer 1

Let the age of son = x
Therefore the present age = 5+x
5 year ago Age of father = 5+x/2
Present age = 5 + x/2 +5

Now.
Sum of Present age = 55
5 + x + 5+ x/2 +5 =55
15 + x + x/2 =55
X+ x /2 = 40
3x/2 = 40
X = 40 *2/3 = 25

Present age of son= 25
And father = 55 - 25 = 30

Answer 2

Let the age of son five years ago = x years
Therefore the age of the father five years ago = 2x years

After five years (i.e at present)
Father's age = (2x + 5) years
Son's age = (x+5) years

Given that the sum of their present ages = 55
2x+5+x+5 = 55
3x + 10 = 55
3x = 45
x = 15

So, the present age of son = 15+5 = 20 years
The present age of father = 2*15 + 5 =35 years