-12.81% is the change from 320 to 279
Calculation steps:
[( 279 - 320 ) ÷ 320] x 100 = -12.81%
Formula
Percentage change = [(279 - 320) / 320] x 100
Subtract the new number by the original number
279 - 320 = -41
-41 ÷ 320 = -0.128125
-0.128125 x 100 = -12.81%