-95% is the change from 400 to 20
Calculation steps:
[( 20 - 400 ) ÷ 400] x 100 = -95%
Formula
Percentage change = [(20 - 400) / 400] x 100
Subtract the new number by the original number
20 - 400 = -380
-380 ÷ 400 = -0.95
-0.95 x 100 = -95%
Example