I've been struggling for a good couple hours on the below, and I was hoping someone might be able to push me int the right direction...

"A" represents the event "the breath analyzer indicates the suspect is drunk" and "B" represents the event "the suspect is drunk." On a given Saturday night, about 5% of drivers are known to be drunk.

If P(A | B) = P(compliment of A | complement of B) = p

a.) determine P(compliment of B | A) if p = .95

b.) how big should p be so that P(B | A) = 0.9?

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From the problem I can deduce that P(B) is .05 and P(compliment of A | B) = (A | compliment of B) = .05, but how can I put P(compliment of B | A) in terms of P(A | B)