-50.49% is the change from 507 to 251
Calculation steps:
[( 251 - 507 ) ÷ 507] x 100 = -50.49%
Formula
Percentage change = [(251 - 507) / 507] x 100
Subtract the new number by the original number
251 - 507 = -256
-256 ÷ 507 = -0.504930966469428
-0.504930966469428 x 100 = -50.49%