If you hold Ax and the flop is Ayz, there are 47 cards left in the deck. Only two of them are aces, which leaves 45 non-ace cards. The number of possible two card hands not containing an ace are therefore 45C2, which equals 990.

The total possible number of two card hands left in the deck is 47C2, which is 1081.

Therefore the probability of at least one person holding an ace is 1 - 990/1081 = 0.084..., or about 8%.