-21.08% is the change from 166 to 131
Calculation steps:
[( 131 - 166 ) ÷ 166] x 100 = -21.08%
Formula
Percentage change = [(131 - 166) / 166] x 100
Subtract the new number by the original number
131 - 166 = -35
-35 ÷ 166 = -0.21084337349397592
-0.21084337349397592 x 100 = -21.08%