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Answer:
The traveler can plan such a tour in 3003 ways.
Step-by-step explanation:
The order that the cities are chosen is not important, since it is chosen by the company and not by the traveler. So we use the combinations formula to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.

In this problem, we have that:
Combinations of 5 cities from a set of 15. So

The traveler can plan such a tour in 3003 ways.
we are given that
f(x) is defined for all values of x except at x=c
Limit may or may not exist
case-1:
If there is hole at x=c , then limit exist
case-2:
If there is vertical asymptote at x=c , then limit does not exist
Examples:
case-1:

We can simplify it



so, we can see that limit exist and it's value defined
case-2:

Left limit is


Right Limit is


so, we can see that left limit is not equal to right limit
so, limit does not exist