-17.97% is the change from 640 to 525
Calculation steps:
[( 525 - 640 ) ÷ 640] x 100 = -17.97%
Formula
Percentage change = [(525 - 640) / 640] x 100
Subtract the new number by the original number
525 - 640 = -115
-115 ÷ 640 = -0.1796875
-0.1796875 x 100 = -17.97%