ok, so i found the link below and im sure this has been explained many times, how can someone try to reexplain the baye formula? I understand its looking at probability with additional information.

http://www.analystforum.com/forums/cfa-forums/cfa-level-i-forum/91307380

Bonds rated B have a 25% chance of default in 5 years. ABonds rated CCC have a 40% chance of defauly in 5 years. A portoflio consists of 30% B and 70% CCC rated bonds. if randomly selected bond defaults in 5 years, what is the probability that it was a B rated bond?

The final step is 0.075/0.355 = .211.

How is your mind processing to get to this point? And you just divide one by another, but the formula below, you divide and then multiply.

Bayes = (probabilty of new info for a given event / unconditional probabilty of a new informaiton) * Prior probability of the event?

THANKS!