The sum of the ages of a father and his son is 50 years. Five years ago, the father's age was 4 times his son's age. Find their present ages.

Correct option is B

Given:
Present age sum: Father + Son = 50 years
5 years ago: Father's age = 4 × Son's age
Formula Used:
Linear simultaneous equations.
Solution:
Let the present age of the father be F and the son be S.
F + S = 50 => F = 50 - S
Five years ago, their ages were F - 5 and S - 5 respectively.
F - 5 = 4(S - 5)
Substitute the value of F from the first equation into the second.
(50 - S) - 5 = 4S - 20
45 - S = 4S - 20
45 + 20 = 4S + S
65 = 5S
S = 13
Substitute S back into the first equation to find F.
F = 50 - 13 = 37
The present age of the father is 37 years and the son is 13 years.
Final Answer
So the correct answer is (b)