(a) In how many ways can 9 people be lined up to get on a bus? (b) If 4 specific persons, among 9, insist on following each other, how many ways are possible? (c) If 2 specific persons, among 9, refuse to follow each other, how many ways are possible? (a) The 9 different people can be lined up in different ways. (b) The people can be lined up in different ways. (c) The people can be lined up in different ways