-40.23% is the change from 517 to 309
Calculation steps:
[( 309 - 517 ) ÷ 517] x 100 = -40.23%
Formula
Percentage change = [(309 - 517) / 517] x 100
Subtract the new number by the original number
309 - 517 = -208
-208 ÷ 517 = -0.402321083172147
-0.402321083172147 x 100 = -40.23%