-39.72% is the change from 506 to 305
Calculation steps:
[( 305 - 506 ) ÷ 506] x 100 = -39.72%
Formula
Percentage change = [(305 - 506) / 506] x 100
Subtract the new number by the original number
305 - 506 = -201
-201 ÷ 506 = -0.39723320158102765
-0.39723320158102765 x 100 = -39.72%