-76.43% is the change from 420 to 99
Calculation steps:
[( 99 - 420 ) ÷ 420] x 100 = -76.43%
Formula
Percentage change = [(99 - 420) / 420] x 100
Subtract the new number by the original number
99 - 420 = -321
-321 ÷ 420 = -0.7642857142857142
-0.7642857142857142 x 100 = -76.43%