-83.73% is the change from 670 to 109
Calculation steps:
[( 109 - 670 ) ÷ 670] x 100 = -83.73%
Formula
Percentage change = [(109 - 670) / 670] x 100
Subtract the new number by the original number
109 - 670 = -561
-561 ÷ 670 = -0.8373134328358209
-0.8373134328358209 x 100 = -83.73%