-79.34% is the change from 668 to 138
Calculation steps:
[( 138 - 668 ) ÷ 668] x 100 = -79.34%
Formula
Percentage change = [(138 - 668) / 668] x 100
Subtract the new number by the original number
138 - 668 = -530
-530 ÷ 668 = -0.7934131736526946
-0.7934131736526946 x 100 = -79.34%