Answer:
80%
Step-by-step explanation:
So the dress originally sold for $50, and it went down by $40 to reach $10. So, because it went down by $40, the way we figure out the percentage we need to figure out the fraction. The fraction is 40/50. So if a percentage is a fraction out of 100, then 40/50 is 80/100. The dress dropped by 80%.
