-79.69% is the change from 640 to 130
Calculation steps:
[( 130 - 640 ) ÷ 640] x 100 = -79.69%
Formula
Percentage change = [(130 - 640) / 640] x 100
Subtract the new number by the original number
130 - 640 = -510
-510 ÷ 640 = -0.796875
-0.796875 x 100 = -79.69%