The sum of the ages of a father and his son is 60 years. Six years ago, the father's age was five times the age of the son. What will be the son's age after 6 years?
Answer: A
Let the present ages of the father and son be F and S.
F + S = 60.
Six years ago, their ages were F-6 and S-6. So, F-6 = 5(S-6) => F - 6 = 5S - 30 => F = 5S - 24.
Substitute this into the first equation: (5S - 24) + S = 60 => 6S = 84 => S = 14.
The son's current age is 14 years. His age after 6 years will be 14 + 6 = 20 years.