The arrangement of classrooms is as follows:
- Class 2 A is at the extreme right.
- Class 5 A is three places away from class 1 A, and it is to the right of class 3 B.
- After applying these conditions, we find that class 5 A is to the immediate right of class 3 B.
In seating or arrangement problems, use the given conditions to place each item step by step, ensuring all restrictions are followed.