Poker odds, answered
99 vs AK odds: pocket nines against ace-king
Pocket nines (9♥ 9♦) win 55.5% of the time against ace-king (A♠ K♣), lose 44.2% and tie 0.3%, all in before the flop. Equity: 55.7% to 44.3%.
Counted exactly over all 1,712,304 boards, not simulated. Equity counts a tie as half a win.
Why 99 is the favourite
This is the classic "coin flip": a pair against two higher cards. The ace-king wins by pairing either card (six outs on each of five cards), the pocket nines win when neither pairs and when they make a set. The pair is a small favourite; the closer it is to the overcards, the less the straights the overcards make matter.
What it means for a call
An all-in call is right when your share of the pot is at least the price. With 44.3% equity, ace-king needs the pot to offer at least 1.3 to 1 to call against exactly pocket nines. In real hands nobody shows their cards: compare your equity against the whole range of hands that would bet this way, in the equity calculator or the preflop odds chart.
Suits change the numbers by a point or two: shared suits take flushes away from one hand. These are the suits shown above.