The Brothers Ages Aptitude Problem is as follows :
Question :
Bharath is 5 years elder than Akash who is 4 years elder than Raghu. The sum of their ages is 61. Find the age of Akash.
Solution :
From the question, it is obvious that Raghu is the youngest brother. Let his age be x.
Now Akash’s age is = x + 4
and Bharaths age is = 5 + Akash’s age = 5 + (x + 4) = x + 9
So sum of all the ages is = x + (x + 4) + (x + 9) => 3x + 13 = 61.
3x = 61 -13 = 48
Implies , x = 48/3 = 16 
This is Raghu’s age. Hence Akash’s age is 16 + 4 = 20 yrs
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You can understand more about solving ages problem, if you watch this lecture on Ages – Basics Cheers!