-34.43% is the change from 976 to 640
Calculation steps:
[( 640 - 976 ) ÷ 976] x 100 = -34.43%
Formula
Percentage change = [(640 - 976) / 976] x 100
Subtract the new number by the original number
640 - 976 = -336
-336 ÷ 976 = -0.3442622950819672
-0.3442622950819672 x 100 = -34.43%