original price: $65
discount: 15% off
sale price: ?
There are two ways you can solve this problem:
Here's the longer way (by one step):
65 * .15 (15% in decimal form) = 9.75
65 - 9.75 = 55.25
sale price = $55.25
Here's the method that's one step shorter:
65 * .85 (100-15 ~ because it's 15%[15/100] off) = 55.25
sale price = $55.25
Either way works for solving discounts/sales.