-78.2% is the change from 399 to 87
Calculation steps:
[( 87 - 399 ) ÷ 399] x 100 = -78.2%
Formula
Percentage change = [(87 - 399) / 399] x 100
Subtract the new number by the original number
87 - 399 = -312
-312 ÷ 399 = -0.7819548872180451
-0.7819548872180451 x 100 = -78.2%