-8.21% is the change from 280 to 257
Calculation steps:
[( 257 - 280 ) ÷ 280] x 100 = -8.21%
Formula
Percentage change = [(257 - 280) / 280] x 100
Subtract the new number by the original number
257 - 280 = -23
-23 ÷ 280 = -0.08214285714285714
-0.08214285714285714 x 100 = -8.21%