Please help with this question. Please provide all steps and calculations. Please don't use answers from other websites, I looked at them and didn't understand them. Thank you

Problem 4. Let X .. X 2. . . . be i.i.d. random variables. Each Xi follows Exponential (A) with the pdf f); ('1') = A941,: 2 0. Let N follow Poisson). Suppose N is independent of the ATS. Let S = 25:] xi- (1). Derive the expected value of S. (2). Derive the variance of S. (3). Derive the covariance between S and N. (4). Derive the moment generating function of S