Answer: 50
Let's first of all assume the son's age as x.
So,
Father's age will be 2x i.e. twice as old as the son
Given that,
Sum of their ages = 75 years
So,
x + 2x = 75
3x = 75
x = 75/3
x = 25
Hence,
Son's age = x = 25 years
Father's age = 2x = 2 * 25 = 50 years