-19.04% is the change from 520 to 421
Calculation steps:
[( 421 - 520 ) ÷ 520] x 100 = -19.04%
Formula
Percentage change = [(421 - 520) / 520] x 100
Subtract the new number by the original number
421 - 520 = -99
-99 ÷ 520 = -0.19038461538461537
-0.19038461538461537 x 100 = -19.04%