-31.88% is the change from 938 to 639
Calculation steps:
[( 639 - 938 ) ÷ 938] x 100 = -31.88%
Formula
Percentage change = [(639 - 938) / 938] x 100
Subtract the new number by the original number
639 - 938 = -299
-299 ÷ 938 = -0.3187633262260128
-0.3187633262260128 x 100 = -31.88%