-78.72% is the change from 390 to 83
Calculation steps:
[( 83 - 390 ) ÷ 390] x 100 = -78.72%
Formula
Percentage change = [(83 - 390) / 390] x 100
Subtract the new number by the original number
83 - 390 = -307
-307 ÷ 390 = -0.7871794871794872
-0.7871794871794872 x 100 = -78.72%