-52.5% is the change from 640 to 304
Calculation steps:
[( 304 - 640 ) ÷ 640] x 100 = -52.5%
Formula
Percentage change = [(304 - 640) / 640] x 100
Subtract the new number by the original number
304 - 640 = -336
-336 ÷ 640 = -0.525
-0.525 x 100 = -52.5%