I don’t see this carpet question as unfair or impractical. It seems to reflect the (perhaps slightly idealized) steps someone would need to take. But maybe they could have used a rug instead, really tied the room together.
Yes, as noted upthread, ChatGPT arrives at the correct answer if given only the final sale price. But if given redundant information in the form of the regular price, the percent discount, and the sale price, it unwisely chooses to ignore the sale price and compute it for itself using the false discount percentage, thereby arriving at an answer that is close but not correct.
The question seems to assume that there will be no waste. And in fact, by introducing an unstated element of common knowledge, one can see that this is true if all dimensions are exactly right, because in North America most residential carpet rolls are 12 feet wide, so a 9-foot length from a standard roll will exactly fit the room, at least in theory.