-80.77% is the change from 520 to 100
Calculation steps:
[( 100 - 520 ) ÷ 520] x 100 = -80.77%
Formula
Percentage change = [(100 - 520) / 520] x 100
Subtract the new number by the original number
100 - 520 = -420
-420 ÷ 520 = -0.8076923076923077
-0.8076923076923077 x 100 = -80.77%