Answer:
25 years old.
Step-by-step explanation:
Given that a man is six times as old as his son, while twenty years later, the man will be twice as old as his son, to find the age of the man when his son was born the following mathematical reasoning must be carried out:
Given that the man is 6X, and after 20 years it becomes 2X, with X being the age of his son, it could be said that those 20 years are equal to 4/6 (6-2 = 4). Therefore, since 20/4 equals 5, and 5 x 6 equals 30, the man is 30 years old and his son is 5.
At the same time, in 20 years, the man will be 50 and his son will be 25, being only twice as big as his son. Therefore, at the time of the birth of his son, the man was 25 years old.