Please help asap

Two random variables X and Y have the joint pmf Pyy (x, y) given below Pyy (x, y) y = 1 y = 2 y = 3 x =-1 O 0.01 O O x = 0 0.09 0.09 x = 1 O no O 1. What should the missing value in the table be? 2. What are the marginal pmfs Py(x) and Py (y) and the joint marginal cdfs Fy(x) and Fy (y)? 3. Are X & Y independent? 4. Let W = X - Y. What is the pmf Pw (w) ? Find E (w) and Var (w)