-12.77% is the change from 321 to 280
Calculation steps:
[( 280 - 321 ) ÷ 321] x 100 = -12.77%
Formula
Percentage change = [(280 - 321) / 321] x 100
Subtract the new number by the original number
280 - 321 = -41
-41 ÷ 321 = -0.1277258566978193
-0.1277258566978193 x 100 = -12.77%