Bag A contains 3 red and 2 black balls, while bag B contains 2 red and 3 black balls. A ball drawn at random from bag A is transferred to bag B and then one ball is drawn at random from bag B. If this ball was found to be a red ball, find the probability that the ball drawn from bag A was red.
Let the events be
E1: transforming a red ball from A to B
E2: transforming a black ball from A to B
A: getting a red ball from bag B