[rufus]

There are 50 unknown cards, so the number of possible flops is
50 choose 3 = (50*49*48)/(3*2*1)
If you're holding 88o there are 24 overcards (A-9 * 4) so there are
(24 choose 0) * (26 choose 3) = 1 * (26*25*24)/(3*2*1)
ways to have no overcards
(24 choose 1) * (26 choose 2) = 24/1 * (26*25)/(2*1)
ways to have one overcard
(24 choose 2) * (25 choose 1) = (24*23)/(2*1) * 26/1
ways to have two overcards
(24 choose 3) * (25 choose 0) = (24*23*22)/(3*2*1) * 1
ways to have three overcards.

So you can take the fractions to figure out your probabilities.