Please help i need it fast PLEASEee

Me. i can't figure out this question. give an explanation too. .

Joe has some money in his bank account he deposits 45$ write an expression that represents the amount of money in joe's account

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?