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Explanation:
There are two approaches we can take.
The first approach is finding the amount we save, which is 5% of 15 = 0.05*15 = 0.75 dollars or 75 cents.
So the new price is 15 - 0.75 = 14.25 dollars
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The second approach is to think of it like this: If you save 5%, then you still have to pay the remaining 95% (the two percentages add to 100%).
95% of 15 = 0.95*15 = 14.25
This second approach is handy if you want to chain multiple discounts together. So let's say there's a special 10% off sale on top of the 5% discount. We would multiply by 0.90 to further discount by 10% and get to 0.90*0.95*15 = 12.825 = 12.83. It also works in reverse too and we could chain percent increases along with percent decreases.