The first outcome is one of A and B the second outcome in each case is one of a and b. Use the following probabilities:

Pr[A] = 2/3
Pr[B] = 1/3
Pr[a given A] = 1/5
Pr[b given A] = 4/5
Pr[a given B] = 1/7
Pr[b given B] = 6/7

Find the following missing probabilities:
1) Pr[B given b] =