-27.5% is the change from 640 to 464
Calculation steps:
[( 464 - 640 ) ÷ 640] x 100 = -27.5%
Formula
Percentage change = [(464 - 640) / 640] x 100
Subtract the new number by the original number
464 - 640 = -176
-176 ÷ 640 = -0.275
-0.275 x 100 = -27.5%