-66.8% is the change from 500 to 166
Calculation steps:
[( 166 - 500 ) ÷ 500] x 100 = -66.8%
Formula
Percentage change = [(166 - 500) / 500] x 100
Subtract the new number by the original number
166 - 500 = -334
-334 ÷ 500 = -0.668
-0.668 x 100 = -66.8%