a chair that cost $210 was reduced by 40% for a one day sale. after the sale, the sale price was increased by 40%. what is the price of the chair?

210, because it you subtract 40%, then add it again, you get the previous outcome, another example would be a soda bottle price it 5.00, they reduce the price by 50%, then the next day raised it 50% then the previous day, the amount stays the same.