-50.48% is the change from 521 to 258
Calculation steps:
[( 258 - 521 ) ÷ 521] x 100 = -50.48%
Formula
Percentage change = [(258 - 521) / 521] x 100
Subtract the new number by the original number
258 - 521 = -263
-263 ÷ 521 = -0.5047984644913628
-0.5047984644913628 x 100 = -50.48%