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Let the age of Rohan be “x” years then age of Nikhil will be (x+8) years.
Therefore, when Rohan will be twice as old as Nikhil then the age of Rohan will be of 8x2=16 years.

Given that, Nikhil is 8 years younger than his brother Rohan.
Let the present age of Nikhil be x years.
Then, the present age of Rohan = x + 8 years.
Now, when Rohan will be twice as old as Nikhil,
Rohan's age = 2(x + 8)
⇒ Rohan's age = 2x + 16 years
Hence, Rohan's age will be 16 years when he will be twice as old as Nikhil.

Explanation:
Age: Age is the length of time that a person has lived or a thing has existed.
Twice as old: Twice as old means to have twice the age of someone or something.

Therefore, in this question, Rohan's age will be 16 years when he will be twice as old as Nikhil.
This is because Nikhil is 8 years younger than Rohan, thus when Rohan's age is 2x+16 years, Nikhil will be x+8 years old.
Hence, the correct option is D 16.

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