-24.41% is the change from 340 to 257
Calculation steps:
[( 257 - 340 ) ÷ 340] x 100 = -24.41%
Formula
Percentage change = [(257 - 340) / 340] x 100
Subtract the new number by the original number
257 - 340 = -83
-83 ÷ 340 = -0.24411764705882352
-0.24411764705882352 x 100 = -24.41%