Answer:
Their vacation lasted 121 days.
Explanation:
Consider the provided information.
A family of five is taking an extended vacation. Every day at lunch they stand in line at a cafeteria in a different order than ever before.
Therefore, the number of possible ways are:


On the last day, however, they can't help repeating a previous order.
That means on the last day they repeat the previous order.
Therefore the total number of ways are:

Hence, their vacation lasted 121 days.