-86.59% is the change from 671 to 90
Calculation steps:
[( 90 - 671 ) ÷ 671] x 100 = -86.59%
Formula
Percentage change = [(90 - 671) / 671] x 100
Subtract the new number by the original number
90 - 671 = -581
-581 ÷ 671 = -0.8658718330849479
-0.8658718330849479 x 100 = -86.59%