-17.97% is the change from 306 to 251
Calculation steps:
[( 251 - 306 ) ÷ 306] x 100 = -17.97%
Formula
Percentage change = [(251 - 306) / 306] x 100
Subtract the new number by the original number
251 - 306 = -55
-55 ÷ 306 = -0.17973856209150327
-0.17973856209150327 x 100 = -17.97%