-38.39% is the change from 521 to 321
Calculation steps:
[( 321 - 521 ) ÷ 521] x 100 = -38.39%
Formula
Percentage change = [(321 - 521) / 521] x 100
Subtract the new number by the original number
321 - 521 = -200
-200 ÷ 521 = -0.3838771593090211
-0.3838771593090211 x 100 = -38.39%