-18.49% is the change from 784 to 639
Calculation steps:
[( 639 - 784 ) ÷ 784] x 100 = -18.49%
Formula
Percentage change = [(639 - 784) / 784] x 100
Subtract the new number by the original number
639 - 784 = -145
-145 ÷ 784 = -0.18494897959183673
-0.18494897959183673 x 100 = -18.49%