Let be the probability of a draw, probability of B winning and the probability of A winning.

Then:





and of course:



or:



so:



as Mr Fantastic has.

Now the ony way out I can see is if the question asked for the odds of a draw since the odds are the ratio of favourable to unfavourable outcomes the odds are .

.

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Yes, I am an agent of Satan, but my duties are largely confined to the legal department.