Tanvir’s present age is two-fifths of the age of his father. After 8 years, Tanvir will be one-half of the age of his father. What is the present age of the father?

Question: Tanvir’s present age is two-fifths of the age of his father. After 8 years, Tanvir will be one-half of the age of his father. What is the present age of the father?

Solution:
Let,
Present age of father = p year
So, Tanvir's present age = p × (2/5) year

After 8 years father will be = (p + 8) year
After 8 years Tanvir will be = {(2p/5) + 8} year

According to the conditions,
(1/2)(p + 8) = {(2p/5) + 8}
or, (p + 8)/2 = (2p + 40)/5
or, 5p + 40 = 4p + 80
or, 5p - 4p = 80 - 40
∴ p = 40

So, Present age of father = 40 years.