Answer:
The percentage of customers who buy an extended warranty is 33%.
Explanation:
In this problem, we have these following percentages.
35% of the customers select the basic camera.
This also means that:
65% of the customers select the deluxe version. (Since you can buy only two versions of the hard disk camera and the sum of the percentages is 100%).
20% of those who select the basic camera also purchase the extended warranty.
40% of those who select the deluxe version also purchase the extended warranty.
What is the percentage of customers who buy an extened warranty?

is the percentage of those who buy the basic version with the extended warranty. So it is 20% of 35%. So

is the percentage of those who buy the deluxe version with the extended warranty. So it is 40% of 65%. So


The percentage of customers who buy an extended warranty is 33%.