-52.94% is the change from 850 to 400
Calculation steps:
[( 400 - 850 ) ÷ 850] x 100 = -52.94%
Formula
Percentage change = [(400 - 850) / 850] x 100
Subtract the new number by the original number
400 - 850 = -450
-450 ÷ 850 = -0.5294117647058824
-0.5294117647058824 x 100 = -52.94%