A father said to his son, ''I was as old as you are at the present at the time of your birth''. If the father's age is 52 years now, then the son's age 8 years back was

Suppose present age of son = P years
Present age of father = 52 years
According to question,
Father's age at son's birth = son's present age
? 52 ? P = P
P + P = 52 years
? 2P = 52
? P = 26 years
Son's age 8 years back = present age of son - 8 years = 26 ? 8 = 18 years