There would be 25 people in the line.
There are 6 people between jane and ken
k - - - - - - j
there are 18 people ahead of jane including ken
- - - - - - - - - - -k - - - - - - j
and 13 people behind ken including jane
- - - - - - - - - - -k - - - - - - j - - - - - -
if you add all of the dashes up from the row above, you will get your answer of 25 people in the line