-18.77% is the change from 309 to 251
Calculation steps:
[( 251 - 309 ) ÷ 309] x 100 = -18.77%
Formula
Percentage change = [(251 - 309) / 309] x 100
Subtract the new number by the original number
251 - 309 = -58
-58 ÷ 309 = -0.18770226537216828
-0.18770226537216828 x 100 = -18.77%