-21.05% is the change from 323 to 255
Calculation steps:
[( 255 - 323 ) ÷ 323] x 100 = -21.05%
Formula
Percentage change = [(255 - 323) / 323] x 100
Subtract the new number by the original number
255 - 323 = -68
-68 ÷ 323 = -0.21052631578947367
-0.21052631578947367 x 100 = -21.05%