help please show organized solution and if your write please make the handwriting understandable thank you verymuch

Exercise 17. Find the distribution of Z = X +Y, if X and Y are jointly continuous random variables with joint PDF given by fx.y(x, y) = 2e-(z+")[10,x] (y) I(0,20) (I). Exercise 19. Let X and Y be two random variables with joint probability density function given by fxx(x, y) = 2e-(2+y)[oz](y) /10,20) (y). Find the joint probability density function of X and X + Y. Exercise 20. Let X] and X2 be iid U(0, 1) random variables. Find the joint probability density function of Y1 = X1 + X2 and Y2 = X2 - X1