Sir, I am stuck on this question

Question 4 Random variables X1, ..., Xn are independent identically distributed. Let s = x1 + x2 + ... +Xn be the n arithmetic mean of the observed values. 1. Assume that each X; is a discrete random variable following a geometric PMF with parameter p given by Px, (xi) = (1 -p)*-'p. Find the maximum likelihood estimator of p in terms of s. 2. Assume that each X; instead is a continuous random variable following an exponential PDF with parameter 0 given by Be-0x1 x 20 fx, (x1) = otherwise. Find the maximum likelihood estimator of 0 in terms of s