If FM is modelled on real life (and unless they went gold before Dublin City went bankrupt) then there'll be 10 teams in the Premier, 9 in the First Division.
Which you'd have been able to find with 60 seconds' worth of web searching, like I did:
Wikipedia's Entry on the League of Ireland
For future reference: if you post in this forum with questions that have absolutely nothing to do with LLM, expect responses like the ones above. And sort your spelling and grammar out whilst you're at it.
I'm in a good mood today, so don't expect answers like this all the time.