-37.4% is the change from 639 to 400
Calculation steps:
[( 400 - 639 ) ÷ 639] x 100 = -37.4%
Formula
Percentage change = [(400 - 639) / 639] x 100
Subtract the new number by the original number
400 - 639 = -239
-239 ÷ 639 = -0.37402190923317685
-0.37402190923317685 x 100 = -37.4%