how do i work out question 10

Questions 9 and 10 refer to the following information. Boxes A and B contain 4 counters each. Box A contains two red and two yellow counters and box B contains three red and one yellow counters. A box is chosen at random and then a single counter is selected. 9 What is the probability of selecting box B and a red counter? TB/E/E TREE TE A 00 1 - B R / RT TRE RE E ET ER D N / - E E ET ER EE 10 What is the probability of selecting a red counter? 1/2 4 A 00 / w B C PCB X PCRE D E