So I believe there is 81 different possibilities for the way 4 games can end up.
1. The first 27, include an Inter win. This would guarantee CL.
2. If Inter draw, they would need Milan to draw or lose. That would be 12 more outcomes that give Inter CL. If Milan were to win here, then we could still get in with a Atalanta loss. That is 9 more chances for us.
3. If Inter lose, we would need both Milan and Roma to draw or lose. This should give us another 12 possible outcomes that work in our favor.
So that means 60 outcomes out of the possible 81 work out in favor for Inter. 74% chance of qualification?
I have no idea if I did that correctly and I probably just wasted 20 minutes of my life for no reason.