-92.5% is the change from 280 to 21
Calculation steps:
[( 21 - 280 ) ÷ 280] x 100 = -92.5%
Formula
Percentage change = [(21 - 280) / 280] x 100
Subtract the new number by the original number
21 - 280 = -259
-259 ÷ 280 = -0.925
-0.925 x 100 = -92.5%
Example