-30.4% is the change from 921 to 641
Calculation steps:
[( 641 - 921 ) ÷ 921] x 100 = -30.4%
Formula
Percentage change = [(641 - 921) / 921] x 100
Subtract the new number by the original number
641 - 921 = -280
-280 ÷ 921 = -0.30401737242128124
-0.30401737242128124 x 100 = -30.4%