-50.29% is the change from 517 to 257
Calculation steps:
[( 257 - 517 ) ÷ 517] x 100 = -50.29%
Formula
Percentage change = [(257 - 517) / 517] x 100
Subtract the new number by the original number
257 - 517 = -260
-260 ÷ 517 = -0.5029013539651838
-0.5029013539651838 x 100 = -50.29%