Percentage Discount given an Original Price of $90 and a Sale Price of $49.50

Discount Rate = 1 –  
Discount Rate = 1 – 0.55
Discount Rate = 0.45
0.45 Converted to a Percent: 0.45 = 45%
Percentage Discount given an Original Price of $90 and a Sale Price of $49.50 = 45%
Note: Reduction in Price = $90 – $49.50 = $40.50