Rhonda is purchasing fencing to go around a rectangular lot which is 4x+9 ft long and 3x-5 ft wide which expression represents the amount of fencing she must buy

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?