-92.31% is the change from 390 to 30
Calculation steps:
[( 30 - 390 ) ÷ 390] x 100 = -92.31%
Formula
Percentage change = [(30 - 390) / 390] x 100
Subtract the new number by the original number
30 - 390 = -360
-360 ÷ 390 = -0.9230769230769231
-0.9230769230769231 x 100 = -92.31%