-49.7% is the change from 507 to 255
Calculation steps:
[( 255 - 507 ) ÷ 507] x 100 = -49.7%
Formula
Percentage change = [(255 - 507) / 507] x 100
Subtract the new number by the original number
255 - 507 = -252
-252 ÷ 507 = -0.4970414201183432
-0.4970414201183432 x 100 = -49.7%