-50% is the change from 330 to 165
Calculation steps:
[( 165 - 330 ) ÷ 330] x 100 = -50%
Formula
Percentage change = [(165 - 330) / 330] x 100
Subtract the new number by the original number
165 - 330 = -165
-165 ÷ 330 = -0.5
-0.5 x 100 = -50%
Example