-50.59% is the change from 85 to 42
Calculation steps:
[( 42 - 85 ) ÷ 85] x 100 = -50.59%
Formula
Percentage change = [(42 - 85) / 85] x 100
Subtract the new number by the original number
42 - 85 = -43
-43 ÷ 85 = -0.5058823529411764
-0.5058823529411764 x 100 = -50.59%