-96.43% is the change from 420 to 15
Calculation steps:
[( 15 - 420 ) ÷ 420] x 100 = -96.43%
Formula
Percentage change = [(15 - 420) / 420] x 100
Subtract the new number by the original number
15 - 420 = -405
-405 ÷ 420 = -0.9642857142857143
-0.9642857142857143 x 100 = -96.43%