Question

Arjun is twice as old as Shriya. Five years ago his age was three times Shriya’s age. Find their present ages.

Answer 1

Let us take Shriya’s present age to be x years. 
Then Arjun’s present age would be 2x years. 
Shriya’s age five years ago was (x – 5) years. 
Arjun’s age five years ago was (2x – 5) years. 
It is given that Arjun’s age five years ago was three times Shriya’s age. 
Thus,           2x – 5 = 3(x – 5) 
or                2x – 5 = 3x – 15 
or                15 – 5 = 3x – 2x 
or                  10 = x 
So, Shriya’s present age = x = 10 years. 
Therefore, Arjun’s present age = 2x = 2 × 10 = 20 years.