-17.9% is the change from 486 to 399
Calculation steps:
[( 399 - 486 ) ÷ 486] x 100 = -17.9%
Formula
Percentage change = [(399 - 486) / 486] x 100
Subtract the new number by the original number
399 - 486 = -87
-87 ÷ 486 = -0.17901234567901234
-0.17901234567901234 x 100 = -17.9%