-87.31% is the change from 670 to 85
Calculation steps:
[( 85 - 670 ) ÷ 670] x 100 = -87.31%
Formula
Percentage change = [(85 - 670) / 670] x 100
Subtract the new number by the original number
85 - 670 = -585
-585 ÷ 670 = -0.8731343283582089
-0.8731343283582089 x 100 = -87.31%