Answer: 20%
Step-by-step explanation: As a fraction, the decrease would be 80/400 as we should know. To find the percentage, you put 80/400 in simplest form which 1/5. And since a fraction is a division problem and you want to find the answer as a percentage, you divide 1 by 5 and get 0.20. To convert a decimal into a percentage, multiply the decimal by 100. This means move the decimal space twice to the right and put a % to get 20%.
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