Jessa drew the picture below by making a rectangle and then drawing triangle QRS inside. The area of triangle QRS is 7 square units, which of the following is NOT the area of one of the other triangles created in the picture, not including QRS?

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?