need guidance on this problem

Problem 3: (Permutations and Combinations) a) How many permutations are there of 11 distinct objects? b) How many 5-permutaions are there of 11 distinct objects? c) In how many ways can we select a chair person, vice-chairperson, secretary, and treasurer from a group of 12 persons d) How many strings can be formed by ordering the letters ABCDE subject to contain the substring ACE? e) How many strings can be formed by ordering the letters ABCDE subject to contain the substring DB and AE? f) In how many ways can we select a committee of five persons from a club consisting of six men and seven women