Ivy checks to see how many people are waiting in line. She notes that there are 120 possible line arrangements for the people that are in line. How many people are waiting to order pizza?

The total number of persons standing in the line waiting for ordering pizza are 5.

Explanation:

There are 5 people in total so the first place can be occupied by any of the 5 persons.

Secondly the second place in the line can be occupied by any of the 4 persons left.

Then the third place will be occupied by any remaining 3 persons as the front two places are already occupied.

Similarly the fourth place will be taken by any of the remaining two people. And lastly the last place will b filled by the last remaining person.

So the total number of ways will be 5*4*3*2*1 = 120 ways that is given in the question.