-12.62% is the change from 309 to 270
Calculation steps:
[( 270 - 309 ) ÷ 309] x 100 = -12.62%
Formula
Percentage change = [(270 - 309) / 309] x 100
Subtract the new number by the original number
270 - 309 = -39
-39 ÷ 309 = -0.1262135922330097
-0.1262135922330097 x 100 = -12.62%