-21.07% is the change from 318 to 251
Calculation steps:
[( 251 - 318 ) ÷ 318] x 100 = -21.07%
Formula
Percentage change = [(251 - 318) / 318] x 100
Subtract the new number by the original number
251 - 318 = -67
-67 ÷ 318 = -0.21069182389937108
-0.21069182389937108 x 100 = -21.07%