How can i determine the sale price if you were given the regular price and percent of markdown

You would multiply the sales regular price by the percent and then subtract your answer from the regular sale price. For example, if something cost $499 and the sales price was 15% off, you would multiply 499 by 0.15 and then you would get 74.85. You would then subtract the 74.89 from the original price which was $499 and you would get $424.11 which would be your new price with the discount.