Percentage Discount given an Original Price of $12 and a Sale Price of $8

Discount Rate = 1 –  
Discount Rate = 1 – 0.6667
Discount Rate = 0.3333
0.3333 Converted to a Percent: 0.3333 = 33.33%
Percentage Discount given an Original Price of $12 and a Sale Price of $8 = 33.33%
Note: Reduction in Price = $12 – $8 = $4