@student4444 there are 30 chairs, on one of the pages it shows the seating chart. First girl doesnt matter where she sits, so theres no chance factor for her. 1/30 x 1/30 = 1/900
@student4444 Assuming you mean only the 3 girls and the seatings of the rest do not matter, there are 25! ways to seat the students and 22! ways have the seatings with the 3 in their specific locations. Hence it looks like the odds are 1/(25*24*23)
I don't know how you'd be able to pick up on the cues daisuke should when every girl around him is already giving them off to some extent, it's become the new ordinary for him