solve each part

2. Suppose we roll a fair six-sided die five times, and toss a fair coin seven times (for a total of 12 trials). We'll consider a die roll a "success" if the result is greater than 2, and we'll also consider a coin toss a "success" if the result is "heads." Let X count the number of successes among the die rolls and let Y count the number of successes among the coin tosses. (a) Find the joint probability mass function of X and Y. (b) Find the probability that we get exactly three successes among the 12 trials. (c) Find E( X - XY?), where by = E(Y)