-79.64% is the change from 668 to 136
Calculation steps:
[( 136 - 668 ) ÷ 668] x 100 = -79.64%
Formula
Percentage change = [(136 - 668) / 668] x 100
Subtract the new number by the original number
136 - 668 = -532
-532 ÷ 668 = -0.7964071856287425
-0.7964071856287425 x 100 = -79.64%