-79% is the change from 400 to 84
Calculation steps:
[( 84 - 400 ) ÷ 400] x 100 = -79%
Formula
Percentage change = [(84 - 400) / 400] x 100
Subtract the new number by the original number
84 - 400 = -316
-316 ÷ 400 = -0.79
-0.79 x 100 = -79%
Example