Explanation

In this question, since the discount is applied only to items priced $100 or more, to figure this question out we are going to need some information about individual prices, not just combined prices. If the prices are clustered tightly around the average of $90, there conceivably might have been no discount at all. But if there is a very cheap item and a very expensive item, there could have been a substantial discount applied. On to the statements, separately first.

Statement (1) gives us some information along the lines of what we was thinking: the prices are not all clustered tightly around $90. Since there are three items, and their average is $90, then they must sum to $270, by the average formula. And most expensive item is $180, so the combined price of the two cheaper items is $90. That means that neither of the other items was priced above $100. So the total discount is known--it's 20% of $180. Therefore Statement (1) is sufficient.

Statement (2) is logically similar. If one item was $10, then the other two add up to $260, borrowing from some of the reasoning above that still applies here. But the discount could work out to be different amounts in different cases, by this statement alone. The $260 could be from items of $200 and $60, and then the discount would be 20% of $200. Or it could be from items of $210 and $50, and the discount would be 20% of $210. Therefore, Statement (2) is insufficient.

The correct answer is (A).