Chiu from Arcadia High School and Harry from St James' School sent in well explained solutions. Harry describes how he solved the problem:
The answer is 6 students. I numbered each of the students, 1 for the front and 25 for the back. Julia was obviously no. 19. I counted from 25 back 14 places (starting with 25 so the solution would be right). I found that Urvisha was no. 12. Then I counted the numbers between 12 and 19 and got 6.
Chiu drew a diagram to help answer the problem:
From the picture above, there are 25 students queuing in a straight line. Since Julia is the 19th from the front, Urvisha is the 14th from the back, which means there are 6 students between Julia and Urvisha.