Sir i am stuck on this question

1. Let X be the random variable that represents the difference between the number of heads and the number of crowns obtained after tossing a balanced coin n times. What are the possible values for x? 2. Suppose that 3 balls are chosen randomly from a set of 3 blue balls, 4 red balls and 5 green balls. If x and Y represent the number of blue balls and the number of red balls, respectively, among the 3 chosen, determine: a. thejoint probability function of X and Y. b. the marginal probability functions of X and Y. c. the expected value of X