-89.74% is the change from 390 to 40
Calculation steps:
[( 40 - 390 ) ÷ 390] x 100 = -89.74%
Formula
Percentage change = [(40 - 390) / 390] x 100
Subtract the new number by the original number
40 - 390 = -350
-350 ÷ 390 = -0.8974358974358975
-0.8974358974358975 x 100 = -89.74%