Final answer:
By applying the principle of inclusion-exclusion, we find that 74% of the retail establishment's customers carry a credit card that the establishment will accept.
Step-by-step explanation:
To calculate the percentage of a retail establishment's customers who carry a credit card that the establishment will accept, we can use the principle of inclusion-exclusion for two sets, where the sets are the customers carrying an American Express card and the customers carrying a VISA card.
Using the given numbers: 24% of customers carry an American Express card, 61% carry a VISA card, and 11% carry both.
The formula for the principle of inclusion-exclusion is: Total = (American Express + VISA) - (Both).
So, we calculate the percentage as follows: (24 + 61) - 11 = 85 - 11 = 74%.
Therefore, 74% of the retail establishment's customers carry a credit card that the establishment will accept.