Martinez landscaping charges $50 flat fee and then $25 per hour. Kassab landscaping charges $65 flat fee and then $20 per hour. How many hours would both landscaping companies have to work for the bill to be the same?

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?