The price s of a sweater is reduced by 25% for a sale. After the sale, the reduced price was increased by 20%. What is the final price of the sweater?

For simplicity, let's say that the original price of the sweater was $100.

It was initially reduced by 25%, which is $25, Hence, the sweater is now $75.

Then, this price was increased by 20% of 75. You can divide 75 by ten and then multiply by two to give 15. We then add this to 75 to give $90.

Therefore, we can say that the final price of the sweater is 90% of the original price.