The original price was $25.
First, convert the 30% to a real mathematical number. For percents, this is always done by dividing the 30% by 100%, or 30% / 100% = 0.300.
Second, find out what 30% of $25 is. This is the amount of the sale discount. This is always found by mulitplying 0.300 by the item's cost $25, like this:
0.300 x $25 = $ 7.50.
So for this sale, you'll save $ 7.50 on this item.
This means, the cost of the item to you is
$25 - $ 7.50 = $17.50.
