i recommend you to read something about the ELO (MMR) rating. every fresh ranked account starts with the default ELO which is somewhere around mid-low silver and is 1300 iirc. your ELO will change every game depending on only 2 things:
- if you win or loose the game
- what the average ELO of both teams is (determined by matchmaking)
the ELO changes for ~12 every game, so +12 when you win, -12 when you loose (im not sure about the exact values here tho)
with some variance in the matchmaking its hard to give you an exact answer to what score places you where, even though the matchmaking tries to place you in games similar to your current ELO. the first 10 games (placements) will give you higher ELO gains and losses (around 4 times the normal value) so as you can see you can end up somewhere around 800-1800 ELO most likely (which is low bronze up to low plat iirc).
with 5-5 you would end up somewhere around mid silver most likely
10-0 would most likely place you in gold 1
7-3 will most of the time place you in high silver or low gold
if youre relatively new to the game and start to play ranked as soon as you hit 30 i'd expect you to maybe go 3-7 or 2-8, what would place you somewhere around mid-high bronze i guess.
if you want to get some more detailled information: https://support.riotgames.com/hc/en-us/articles/201752954-Matchmaking-Guide