-20.9% is the change from 641 to 507
Calculation steps:
[( 507 - 641 ) ÷ 641] x 100 = -20.9%
Formula
Percentage change = [(507 - 641) / 641] x 100
Subtract the new number by the original number
507 - 641 = -134
-134 ÷ 641 = -0.20904836193447737
-0.20904836193447737 x 100 = -20.9%