How many games i need to lose to get demoted from Silver 3 to Silver 4?

Hello, this is my first ranked season and i have 5w 5l and i am now in Silver 3 0lp, i am wondering how many games i need to lose to get demoted to Silver 4? Op.gg says i have 1,398 mmr (Silver 2). And what will happen if i dont play ranked untill next season (will i get demoted or and when?)

-Party :D