Find the missing length of the triangles it’s OK if you can only do one

100 points, hi, i’m not sure how to get the equation from the graph and table.

The area of square garden is 300m squared. how long is the diagonal?

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?