Moving against the blind

[PokerSponge]

David wrote:
First, let's take the case of the opponent who needs a pair of sevens or ace-king or ace-queen to call. That's 80 combinations (six each of the pairs and sixteen each of the non-pairs). You will then be called 80 out of 1,225 times. (1,225 = (50x49)/2).

When you are called you will win about 23 of the 80 times. See why? Thus if you move in $X 1,225 times you will win $100 1,145 times, win $X 23 times, and lose $X 57 times

I don't see why you win 23 of the 80 times. Could someone help me please. I have tried many different calculations but don't see how he arrives at 23.