For a simultaneous equation in x and y if Dr=-25, Dy=50 and D=5. What is the value of x ?
a) -5
b) 1/5
c) 10
15
31​

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?