Given u = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, a = {2, 4, 6, 8, 10, 12, 14}, b = {1, 2, 3, 4, 5, 6, 7} and c = {3, 4, 7, 9, 10, 11, 13, 15}, find each of the following: a. a intersection b intersection c b. c - (b intersection a)