-8.85% is the change from 339 to 309
Calculation steps:
[( 309 - 339 ) ÷ 339] x 100 = -8.85%
Formula
Percentage change = [(309 - 339) / 339] x 100
Subtract the new number by the original number
309 - 339 = -30
-30 ÷ 339 = -0.08849557522123894
-0.08849557522123894 x 100 = -8.85%