-10% is the change from 310 to 279
Calculation steps:
[( 279 - 310 ) ÷ 310] x 100 = -10%
Formula
Percentage change = [(279 - 310) / 310] x 100
Subtract the new number by the original number
279 - 310 = -31
-31 ÷ 310 = -0.1
-0.1 x 100 = -10%
Example