-23.75% is the change from 640 to 488
Calculation steps:
[( 488 - 640 ) ÷ 640] x 100 = -23.75%
Formula
Percentage change = [(488 - 640) / 640] x 100
Subtract the new number by the original number
488 - 640 = -152
-152 ÷ 640 = -0.2375
-0.2375 x 100 = -23.75%