How are these numbers calculated?

Big Games

How we did last week and who we should root for this week.   Explain

Week of 2/5100.0*Chance wins title
South Lyon 5 Brighton 25 +3.5
Howell 22 Pinckney 8 +0.5
Week of 2/9100.0*Chance wins title
South Lyon East 9 Howell 21 Yes
Week of 2/16None
Games Above .500
Chance Will Win Championship