How do I calculate the percentage of discount?

I feel silly asking, but how do I calculate the percentage of discount given using my calculator?



For example, the usual price of an item is $0.81 , but now the price is $0.67 - need to know what percent that has been discounted.



ThanksHow do I calculate the percentage of discount?
Let x be the percentage of the discount.

0.81x = 0.81 - 0.67

0.81x = 0.14

x = 0.14/0.81

x = 0.17 or 17%

Just subtract the new price from the old price. Then divide the difference to the old price.