-20.27% is the change from 666 to 531
Calculation steps:
[( 531 - 666 ) ÷ 666] x 100 = -20.27%
Formula
Percentage change = [(531 - 666) / 666] x 100
Subtract the new number by the original number
531 - 666 = -135
-135 ÷ 666 = -0.20270270270270271
-0.20270270270270271 x 100 = -20.27%