https://www.manifatravel.com/trip/luang-prabang-world-heritage-pak-ou-caves-mekong-river-sunset-cruise-f24/
€177 for the first person or solo traveler.
€22 per person
If your group is more than 2 people, $190 for the first person, $20 for each additional person.
For 4 people, (177 X 1) + (22X3) = €243 (so €60.75 per person)