How do you calulate a markdown or 25 percent?

discount means a deduction from the regular price of something

formula for getting the MARKDOWN or discount:

discounted price = regular price minus (% off multiplied by the regular price)

Example:

30% off of $100

= 30% discount applied to $100

= $100 - (30% * $100)

= $100 - (0.30 * $100)

= $100 - $30

= $70