It's totally different from any other show and they explain it about 80 times every season, but here it is. The judges give them scores 1-10 and then they calculate each contestant's percentage of the total points given to everyone, and then add that to the percentage of votes they receive.

For example, say these were the judges' scores each of these 3 people:

Topanga - 30/30
OJ Simpson - 20/30
Bea Arthur - 10/30

So 60 total points were given out, making their percentages of total points:

Topanga - 30/60 = 50%
OJ Simpson - 33.3%
Bea Arthur - 16.7%

Then say this is what they got in the fan vote:

Topanga - 15%
OJ - 25%
Bea - 60%

They'd then add those to the judge percentages for the final scores:

Topanga - 65%
OJ - 58.3%
Bea - 76.7%

whew

So OJ would go home, even though he had the second highest judged scores and second most votes. It's actually a good system since your performances can save you if you're unpopular and your fanbase can save you if you suck (to a certain point anyway). Most seasons have hilariously shitty popular people go far, like Jerry Springer and Marie Osmond. I don't really see anyone fitting into that category this season though.

I don't think Kim or Brooke will go very far either, unless they're amazing. They both have popular partners though, so that could help a little.

ps Topanga, OJ, and Bea should totes be on next season.