-12.3% is the change from 309 to 271
Calculation steps:
[( 271 - 309 ) ÷ 309] x 100 = -12.3%
Formula
Percentage change = [(271 - 309) / 309] x 100
Subtract the new number by the original number
271 - 309 = -38
-38 ÷ 309 = -0.12297734627831715
-0.12297734627831715 x 100 = -12.3%