There are 25 children i the lunch queue, including nik.

Nik says,

"There are twice as many people in front of me as there are behind me."

How many children are in front of Nik.

12 in front and 12 in back.

Let x be the people in front and y be the people behind him. Nick is the extra person, or the "1"

x+y+1=25

and

x=2y

Substitute 2y for x.

2y+y+1=25

3y+1=25

3y=24

y=8

Now, plug in 8 for y.

x=2y

x=16

16 people are in front of Nik.