-16.9% is the change from 509 to 423
Calculation steps:
[( 423 - 509 ) ÷ 509] x 100 = -16.9%
Formula
Percentage change = [(423 - 509) / 509] x 100
Subtract the new number by the original number
423 - 509 = -86
-86 ÷ 509 = -0.16895874263261296
-0.16895874263261296 x 100 = -16.9%