-79.73% is the change from 666 to 135
Calculation steps:
[( 135 - 666 ) ÷ 666] x 100 = -79.73%
Formula
Percentage change = [(135 - 666) / 666] x 100
Subtract the new number by the original number
135 - 666 = -531
-531 ÷ 666 = -0.7972972972972973
-0.7972972972972973 x 100 = -79.73%