-50.58% is the change from 172 to 85
Calculation steps:
[( 85 - 172 ) ÷ 172] x 100 = -50.58%
Formula
Percentage change = [(85 - 172) / 172] x 100
Subtract the new number by the original number
85 - 172 = -87
-87 ÷ 172 = -0.5058139534883721
-0.5058139534883721 x 100 = -50.58%