-83.59% is the change from 390 to 64
Calculation steps:
[( 64 - 390 ) ÷ 390] x 100 = -83.59%
Formula
Percentage change = [(64 - 390) / 390] x 100
Subtract the new number by the original number
64 - 390 = -326
-326 ÷ 390 = -0.8358974358974359
-0.8358974358974359 x 100 = -83.59%