-17.29% is the change from 509 to 421
Calculation steps:
[( 421 - 509 ) ÷ 509] x 100 = -17.29%
Formula
Percentage change = [(421 - 509) / 509] x 100
Subtract the new number by the original number
421 - 509 = -88
-88 ÷ 509 = -0.17288801571709234
-0.17288801571709234 x 100 = -17.29%