-91.15% is the change from 339 to 30
Calculation steps:
[( 30 - 339 ) ÷ 339] x 100 = -91.15%
Formula
Percentage change = [(30 - 339) / 339] x 100
Subtract the new number by the original number
30 - 339 = -309
-309 ÷ 339 = -0.911504424778761
-0.911504424778761 x 100 = -91.15%