-57.03% is the change from 640 to 275
Calculation steps:
[( 275 - 640 ) ÷ 640] x 100 = -57.03%
Formula
Percentage change = [(275 - 640) / 640] x 100
Subtract the new number by the original number
275 - 640 = -365
-365 ÷ 640 = -0.5703125
-0.5703125 x 100 = -57.03%