One question
Who is selling 78+ xp and what is the price?
And how do i get to lvl 85
1.
Try searching in "Trade" section of the forum -
https://forumen.rpg-club.net/index.php/board,280.0.html Otherwise, try to catch up some1 selling exp ingame... in Giran most likely

2.
By hard work and many hours spent ingame, of course

.
In case you just do not have enough time necessary to level up relatively fast, you can always help yourself by :
- Buying PA service ( after loging in to your account on the website ), which gives you bonus exp.
- Visiting NPC Galent ingame and buy some helpfull consumables for yourself, which can boost your exp rate too.
( box of experience, nevit's hourglass flasks, ocassional vitality flasks [ Xmas holidays f.e. ] )