-40.36% is the change from 669 to 399
Calculation steps:
[( 399 - 669 ) ÷ 669] x 100 = -40.36%
Formula
Percentage change = [(399 - 669) / 669] x 100
Subtract the new number by the original number
399 - 669 = -270
-270 ÷ 669 = -0.40358744394618834
-0.40358744394618834 x 100 = -40.36%