Final answer:
The expression that can be used for the total number of cruise ships in the harbor on all 5 days is 5 * x, where x represents the number of cruise ships on each day.
Step-by-step explanation:
To find the total number of cruise ships in the harbor on all 5 days, you can use the expression:
5 * x
where x represents the number of cruise ships on each day. Multiplying the number of ships on each day by 5 gives you the total number of ships for all 5 days.