97∘ angles in mathematics

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?

If value of cos330° is √3/2 then find tan165°.

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.