Imagine a question and stream-of-consciousness explanation for which this is the answer: 640
Question: A survey conducted by the school showed that only 20% of the 800 parents agree to a tuition fee increase. How many parents disagree with the tuition fee increase?
Stream-of-consciousness: There were 800 x 20 / 100 = 160 parents who agreed to the tuition fee increase. So, there were 800 - 160 = 640 parents who disagreed.