Guild Wars 2

I just got a offensive slot ring from my daily fotm.

I randomly searched on google and it says offensive infusino slot takes 225 relic and defensive takes 75 relic?

But when I went to the fotm vendor there is only the versatile simple infusion which cost 75 relic. So I’m quite confused.

Also can I use the versatile simple infusion in my offensive infusion ring?

There are no different NPC infusions anymore. They removed the defensive infusion and lowered the cost of versatile one to 75, meaning you can use versatile into any slot.
Source:
https://forum-en.gw2archive.eu/forum/info/news/Game-Update-Notes-December-14-2012/first#post1061889
“The simple infusion for defensive slots has been removed from the vendors, and the cost of the versatile simple infusion has been lowered to 75 tokens.”