1/2÷2/3=1/2×_/2=3/_

please help on the blank spaces. thank you

What is the solution to the system of the equations? x = y - 3 x + 3y = 13

Me because some of question i don’t understand

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?