I'm assuming it's the 0.22 = (1/44)([10*3 + 9*1]/4) that you're confused about.
He's basically calculating villain's equity with his range of {JJ, AcKc}. He does this by hand. Since there are three combinations of jacks, he counts this three times, and since there is one combination of AcKc, he counts this once. For ease of writing here, we'll say he has jacks three times and AKcc once. When villain has jacks, he has 10/44 equity or 23%. Since he has this three times, we'll multiply this by three and get 30/44 or 68.18%. Now, with AKcc, he has nine outs giving him 9/44 equity or 20%. He has this once so we only count it once. We add 9/44 to 30/44 to get 39/44 or we can add the 20% to 68.18% and get 88.18%. Now remember that this is an average so we must divide by the total number of samples so we divide by four (three pairs jacks + one AKcc). We now have villain's equity (22% or 9.75/44).
Luckily for us, it's 2010 and we don't have to do calculations like this. We have PokerStove to calculate our (and villain's) equity. Here is the same exact hand, PokerStove style:
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176 games 0.005 secs 35,200 games/sec
Board: Jc 7c 3s 4d
Dead:
equity win tie pots won pots tied
Hand 0: 77.841% 77.84% 00.00% 137 0.00 { 6d5d }
Hand 1: 22.159% 22.16% 00.00% 39 0.00 { JJ, AcKc }
---
We can replace the 4d on the turn with the 4c and we get the 42% that Sklansky provided us in his second calculation:
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176 games 0.005 secs 35,200 games/sec
Board: Jc 7c 3s 4c
Dead:
equity win tie pots won pots tied
Hand 0: 57.955% 57.95% 00.00% 102 0.00 { 6d5d }
Hand 1: 42.045% 42.05% 00.00% 74 0.00 { JJ, AcKc }
---
Now, his third calculation is a simple average of the four possible outcomes (4c/d/s/h turn). I'll make it simple and skip the fractions. We'll go straight to the percentages we calculated before of 22% and 42%. We count 22% three times since that was villain's equity when we landed a 4d/s/h and we count 42% once since that was villain's equity for the one 4c. 22% + 22% + 22% + 42% = 108%. 108% divided by the four outcomes (remember, this is how we compute averages) is 27%; just as seen in the book.
I know it sucks for me to do math in words, but that's really the only way I can do so in a forum. If you're still curious, sign onto IRC and I'll have no problem showing you this Math via Teamviewer and Paint or something.
Extra note: I just noticed that it may be the 1/44 that confuses a lot of people here. Remember, this can easily be distributed and read as [(10/44)(3) + (9/44)(1)]/4. Sklansky decided here to factor out the 1/44 for ease of writing.
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