Could you tell me when should I consider different ranges of Z. And how to figure out the upper/lower bound of the integration

3. (20 marks) Let X and Y be two independent random variables where X follows an exponential distribution with mean 1 and Y follows a uniform distribution over [0, 1]. (a) (10 marks) Calculate P(X > Y). (b) (10 marks) Let Z = X + 2Y. Derive the cumulative distribution of Z