-17.9% is the change from 620 to 509
Calculation steps:
[( 509 - 620 ) ÷ 620] x 100 = -17.9%
Formula
Percentage change = [(509 - 620) / 620] x 100
Subtract the new number by the original number
509 - 620 = -111
-111 ÷ 620 = -0.17903225806451614
-0.17903225806451614 x 100 = -17.9%