Question

a 100 dollar coat is on sale for %20 off the regular price. if the coat's price were raisd back to $100, how much of a percent increase would this be?

Answer 1

If the $100 coat is on sale for 20% off, that means it is being sold for $100 - (20% of $100) = $100 - $20 = $80.
If it is then raised back to $100, we take the difference, and find out what percentage of the selling price it is. The difference is $20, and $20/$80 = 0.25.
So going from $80 to $100 is a 25% increase.