please help solve

31. (7 points) {a,b); L1 = {8, aa, ab }; L2 = { w : no two adjacent characters in ware the same); L3 = { w : w is the first, third, or fifth string in a lexicographic ordering of Lb and { w : w does not start and end with different symbols). As examples, baab E L2. 31.a (2 points) L1 u L3 = R E 31.c (2 points) L1-L2 = 31.d (1 points) L1-(L3 n L.) = {