You are creating a flower arrangement for a friend. the total cost in dollars for one vase and f flowers is given by the expression 8+2.5f how much will it cost to make an arrangement with eight flowers

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?