-30.99% is the change from 939 to 648
Calculation steps:
[( 648 - 939 ) ÷ 939] x 100 = -30.99%
Formula
Percentage change = [(648 - 939) / 939] x 100
Subtract the new number by the original number
648 - 939 = -291
-291 ÷ 939 = -0.30990415335463256
-0.30990415335463256 x 100 = -30.99%