So we need to choose 9 people from the 12 persons.
Here the order of arrangement of the 9 persons is relevant.
So the answer is 12 Permutation 9 = ¹²P₉
¹²P₉ = (12!) / (12 - 9)!
= (12!) / 3!
= (12 * 11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3!) / 3!
= 12 * 11 * 10 * 9 * 8 * 7 * 6 * 5 * 4
= 79 833 600
= 79 833 600 different orders