Solution; 

Let us take Anil's age as 'x' , Vivek's age as 'y' and Tarun's age as 'z'.

It is given that,

No.of years Anil is younger to Vivek = No.of years Anil is elder to Tarun and 

Let us take that no.of years as 'a'. So,

y - x = a ------> 1 

x - z = a ------> 2 

Equating equation 1 and 2 we get 

y - x = x - z 

y + z = x + x

y + z = 2x 

It is also given that, y + z = 48 using this we get

2x = 48

x = 48/2

x = 24

So Anil is 24 years old.

The correct option is 3). 24