What rank will i be?

Depends on your MMR

It's entirely dependent on what your MMR is. It's possible for you to get into a higher tier if you have good MMR, though on average most people drop 2-3 instead due to the soft reset.

whatever you finished last season + league average + points gained/lost during placement/2=rank

Normally its about a couple division lower than where you were... on extreme sides you could drop entire tiers from silver to bronze etc..

probably in silver; trust me riot punish players who put in work and rewards those who lacks skill. just like our sh1ty government taxing the hard working citizens and reward those criminals and low-life welfare recipients with free housing, food and education; it's way of them "balancing" the system.

I have a friend who was 4-6 in placement and got placed in bronze 5 despite being silver the previous season.