Answer:
The odds against the event are 9:11.
Explanation:
The odds being in favor and against an event are complemmentary, that is, their sum is 100% = 1.
The odds in favor of an event are 2:9.
So for each 2 times the event will happen, it wont happen 9 times, in a total of 2 + 9 = 11
So the odds against the event are 9:11.