-83.51% is the change from 661 to 109
Calculation steps:
[( 109 - 661 ) ÷ 661] x 100 = -83.51%
Formula
Percentage change = [(109 - 661) / 661] x 100
Subtract the new number by the original number
109 - 661 = -552
-552 ÷ 661 = -0.8350983358547656
-0.8350983358547656 x 100 = -83.51%