Dennis had x dollars to buy 5 pencils. If he were to buy all five, he would spend all the money he had. Instead, he bought just two pencils. How much money does he have left?

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?