-4.38% is the change from 320 to 306
Calculation steps:
[( 306 - 320 ) ÷ 320] x 100 = -4.38%
Formula
Percentage change = [(306 - 320) / 320] x 100
Subtract the new number by the original number
306 - 320 = -14
-14 ÷ 320 = -0.04375
-0.04375 x 100 = -4.38%