-19% is the change from 642 to 520
Calculation steps:
[( 520 - 642 ) ÷ 642] x 100 = -19%
Formula
Percentage change = [(520 - 642) / 642] x 100
Subtract the new number by the original number
520 - 642 = -122
-122 ÷ 642 = -0.19003115264797507
-0.19003115264797507 x 100 = -19%