The probability of getting a sum 9 when two dice are thrown is

If $$A$$ and $$B$$ are two events such that $$P(B) \neq 0$$ and $$P(B) \neq 1$$, then $$P(\bar{A} \mid \bar{B})$$ is

Two brothers $$X$$ and $$Y$$ appeared for an exam. Let $$A$$ be the event that $$X$$ has passed the exam and $$B$$ is the event that $$Y$$ has passed. The probability of $$A$$ is $$\frac{1}{7}$$ and of $$B$$ is $$\frac{2}{9}$$. Then, the probability that both of them pass the exam is