-12.81% is the change from 640 to 558
Calculation steps:
[( 558 - 640 ) ÷ 640] x 100 = -12.81%
Formula
Percentage change = [(558 - 640) / 640] x 100
Subtract the new number by the original number
558 - 640 = -82
-82 ÷ 640 = -0.128125
-0.128125 x 100 = -12.81%