Know the sale price and the discount applied? Work backwards to find the original price before the discount.
The formula is: Original Price = Sale Price / (1 − Discount / 100).
Example: an item costs $72 after a 10% discount → $72 / (1 − 0.10) = $72 / 0.90 = $80 original price.
$60 / (1 − 0.25) = $60 / 0.75 = $80.
Because the discount % was calculated from the original, not the sale price. Adding 20% back to $80 gives $96, not $100. You must divide by (1 − discount/100) instead.
Yes — the same formula works for any reduction. If a price includes 21% VAT, divide by 1.21 to find the pre-tax amount.