-17% is the change from 200 to 166
Calculation steps:
[( 166 - 200 ) ÷ 200] x 100 = -17%
Formula
Percentage change = [(166 - 200) / 200] x 100
Subtract the new number by the original number
166 - 200 = -34
-34 ÷ 200 = -0.17
-0.17 x 100 = -17%
Example