-80% is the change from 455 to 91
Calculation steps:
[( 91 - 455 ) ÷ 455] x 100 = -80%
Formula
Percentage change = [(91 - 455) / 455] x 100
Subtract the new number by the original number
91 - 455 = -364
-364 ÷ 455 = -0.8
-0.8 x 100 = -80%
Example