The age of the father 5 years ago was 5 times the age of his son. At present the father's age is 3 times that of his son . What is the present age of the father?

Let us assume the present age of father = F year and Son's present age = S years
According to question, 5 years ago,
Father's age = F - 5 and Son's age = S - 5.
According to the question,
The age of the father 5 years ago was 5 times the age of his son.
F - 5 = 5(S - 5)
F - 5 = 5S - 25.....................(1)
At present the father's age is 3 times that of his son.
F = 3S.................................(2)
Put the value of F from equation (2) in equation (1), we will get
⇒ 3S - 5 = 5S - 25
⇒ 25 - 5 = 5S - 3S
⇒ 20 = 2S
⇒ 10 = S
⇒ S = 10.
Put the value of S in Equation (2). we will get,
F = 3S = 3 x 10 = 30
So the present Age of Father = 30.